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ELECTROLUMINESCENT DEVICE

20220399506 · 2022-12-15

    Inventors

    Cpc classification

    International classification

    Abstract

    Provided is an electroluminescent device. The organic electroluminescent device comprises an anode, a cathode and an organic layer disposed between the anode and the cathode, where the organic layer comprises a first compound having a structure of H-L-E and a second compound comprising a ligand L.sub.a having a structure of Formula C. Such a new material combination consisting of the first compound and the second compound can obtain higher efficiency in the device, significantly extend a lifetime, and provide better device performance. Further provided are a display assembly comprising the electroluminescent device and a compound combination.

    Claims

    1. An electroluminescent device, comprising: an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer contains at least a first compound and a second compound; wherein the first compound has a structure of H-L-E, wherein the H has a structure represented by Formula A: ##STR00150## wherein in Formula A, Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N, Z.sub.4 and Z.sub.5 are, at each occurrence identically or differently, selected from CR.sub.z2, and two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring; L is selected from a single bond, substituted or unsubstituted arylene having 6 to 30 carbon atoms, substituted or unsubstituted heteroarylene having 3 to 30 carbon atoms or a combination thereof, E is selected from substituted or unsubstituted aryl having 6 to 30 carbon atoms or substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms; R.sub.z1 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, R.sub.z2 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.z1, R.sub.z2 can be optionally joined to form a ring; wherein the second compound is a metal complex, wherein the metal is selected from a metal with a relative atomic mass greater than 40, and the metal complex comprises a ligand L.sub.a which has a structure represented by Formula C: ##STR00151## wherein in Formula C, the ring A and the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 30 carbon atoms or a heteroaromatic ring having 3 to 30 carbon atoms; R.sub.i represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; and R.sub.ii represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; Y is selected from SiR.sub.yR.sub.y, GeR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se; when two R.sub.y are present, the two R.sub.y may be identical or different; X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N; R, R.sub.i, R.sub.ii, R.sub.x and R.sub.y are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.i, R.sub.x, R.sub.y, R and R.sub.ii can be optionally joined to form a ring.

    2. The electroluminescent device according to claim 1, wherein in Formula A, the two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring, and the ring has at least six ring atoms; preferably, the two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring, and the ring has at least seven ring atoms.

    3. The electroluminescent device according to claim 1, wherein in the first compound, the H has a structure represented by any one of Formula A-1 to Formula A-8: ##STR00152## wherein in Formula A-1 to Formula A-8, Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N; Z.sub.h1 to Z.sub.h8 are, at each occurrence identically or differently, selected from CR.sub.zh or N; Z.sub.m is selected from CR.sub.zm or N; Z.sub.n is selected from CR.sub.znR.sub.zn, O, S or NR.sub.zn; wherein when Z.sub.n is selected from CR.sub.znR.sub.zn, two R.sub.zn may be identical or different; R.sub.z1, R.sub.zh, R.sub.zm and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.z1, R.sub.zh, R.sub.zm, R.sub.zn can be optionally joined to form a ring.

    4. The electroluminescent device according to claim 3, wherein in Formula A-1 to Formula A-8, R.sub.z1, R.sub.zh, R.sub.zm and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, cyano, isocyano, hydroxyl, a sulfanyl group and combinations thereof, and adjacent substituents R.sub.z1, R.sub.zhh, R.sub.zm, R.sub.zn can be optionally joined to form a ring.

    5. The electroluminescent device according to claim 1, wherein the H is selected from the group consisting of the following structures: ##STR00153## ##STR00154## ##STR00155## ##STR00156## ##STR00157## ##STR00158## ##STR00159## wherein optionally, hydrogen in the structures of H-1 to H-76 can be partially or fully substituted with deuterium.

    6. The electroluminescent device according to claim 1, wherein in the first compound, the E has a structure represented by Formula E-a or Formula E-b: ##STR00160## wherein in Formula E-a and Formula E-b, E.sub.1 to E.sub.14 are, at each occurrence identically or differently, selected from C, CR.sub.e or N; R.sub.e is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, adjacent substituents R.sub.e can be optionally joined to form a ring; preferably, in Formula E-a, at least two of E.sub.1 to E.sub.6 are N; in Formula E-b, at least two of E.sub.7 to E.sub.14 are N; more preferably, in Formula E-a, three of E.sub.1 to E.sub.6 are N; in Formula E-b, two of E.sub.7 to E.sub.10 are N.

    7. The electroluminescent device according to claim 1, wherein in the first compound, the E has a structure represented by any one of Formula E-1 to Formula E-10: ##STR00161## wherein in Formula E-1 to Formula E-10, R.sub.A represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; V is selected from O, S or Se; R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.A can be optionally joined to form a ring; preferably, the E has a structure represented by any one of Formula E-11 to Formula E-21: ##STR00162## wherein R.sub.A represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; V is selected from O, S or Se; and R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms and combinations thereof.

    8. The electroluminescent device according to claim 7, wherein in Formula E-1 to Formula E-21, R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, cyano, hydroxyl, a sulfanyl group, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, adjacent substituents R.sub.A can be optionally joined to form a ring; preferably, R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, fluorine, cyano, hydroxyl, a sulfanyl group, methyl, trideuteriomethyl, vinyl, phenyl, biphenyl, naphthyl, 4-cyanophenyl, dibenzofuranyl, dibenzothienyl, triphenylene, carbazolyl, 9-phenylcarbazolyl, 9,9-dimethylfluorenyl, pyridyl, phenylpyridyl and combinations thereof.

    9. The electroluminescent device according to claim 7, wherein in Formula E-1 to Formula E-21, at least one R.sub.A is present, and the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, halogen, cyano, hydroxyl, a sulfanyl group, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, adjacent substituents R.sub.A can be optionally joined to form a ring; preferably, the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, halogen, cyano, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, more preferably, the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, fluorine, cyano, methyl, trideuteriomethyl, phenyl, biphenyl, naphthyl, 4-cyanophenyl, dibenzofuranyl, dibenzothienyl, triphenylene, carbazolyl, 9-phenylcarbazolyl, 9,9-dimethylfluorenyl, pyridyl, phenylpyridyl and combinations thereof.

    10. The electroluminescent device according to claim 1, wherein in the first compound, the E is selected from the group consisting of the following structures: ##STR00163## ##STR00164## ##STR00165## wherein “custom-character” represents a position where the structure of E is joined to the L.

    11. The electroluminescent device according to claim 1, wherein the L is selected from the group consisting of: a single bond, phenylene, naphthylene, biphenylene, terphenylene, triphenylenylene, pyridylene, dibenzothienylene, dibenzofuranylene and thienylene; optionally, hydrogen in the above groups can be partially or fully substituted with deuterium; preferably, the L is selected from the group consisting of the following structures: a single bond ##STR00166## wherein “*” represents a position where the structure of L is joined to the H, and “custom-character” represents a position where the structure of L is joined to the E; optionally, hydrogen in the above structures of L-1 to L-22 can be partially or fully substituted with deuterium.

    12. The electroluminescent device according to claim 1, wherein the first compound has the structure of H-L-E, wherein the H is selected from any one of the group consisting of H-1 to H-76, the L is selected from any one of the group consisting of L-0 to L-22, and the E is selected from any one of the group consisting of E-1 to E-38; optionally, hydrogen in the structure of the first compound can be partially or fully substituted with deuterium; preferably, the first compound is selected from the group consisting of the following structures: ##STR00167## ##STR00168## ##STR00169## ##STR00170## ##STR00171## ##STR00172## ##STR00173## ##STR00174## ##STR00175## ##STR00176## ##STR00177## ##STR00178## ##STR00179## ##STR00180## ##STR00181## ##STR00182## ##STR00183## ##STR00184## ##STR00185## ##STR00186## wherein optionally, hydrogen in the above structures can be partially or fully substituted with deuterium.

    13. The electroluminescent device according to claim 1, wherein in Formula C, the ring A and/or the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 18 carbon atoms or a heteroaromatic ring having 3 to 18 carbon atoms; and preferably, the ring A and/or the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 10 carbon atoms or a heteroaromatic ring having 3 to 10 carbon atoms.

    14. The electroluminescent device according to claim 1, wherein in the second compound, the L.sub.a has a structure represented by any one of Formula 2-1 to Formula 2-19: ##STR00187## ##STR00188## ##STR00189## ##STR00190## wherein in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N, X.sub.3 to X.sub.7 are, at each occurrence identically or differently, selected from CR.sub.i or N, and A.sub.1 to A.sub.6 are, at each occurrence identically or differently, selected from CR.sub.ii or N; Z is, at each occurrence identically or differently, selected from CR.sub.iiiR.sub.iii, SiR.sub.iiiR.sub.iii, PR.sub.iii, O, S or NR.sub.iii; wherein when two R.sub.iii are present, the two R.sub.iii are identical or different; Y is selected from SiR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se; wherein when two R.sub.y are present, the two R.sub.y are identical or different; R, R.sub.x, R.sub.y, R.sub.i, R.sub.ii and R.sub.iii are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof; adjacent substituents R, R.sub.x, R.sub.y, R.sub.i, R.sub.ii and R.sub.iii can be optionally joined to form a ring; preferably, L.sub.a is selected from a structure represented by any one of Formula 2-1, Formula 2-5, Formula 2-8, Formula 2-10, Formula 2-11 or Formula 2-12; more preferably, L.sub.a is selected from a structure represented by Formula 2-1.

    15. The electroluminescent device according to claim 14, wherein in Formula 2-1 to Formula 2-19, at least one of X.sub.1 to X.sub.n and/or A.sub.1 to A.sub.m is selected from N, wherein the X.sub.n corresponds to one of X.sub.1 to X.sub.7 that has the largest number in any one of Formula 2-1 to Formula 2-19, and the A.sub.m corresponds to one of A.sub.1 to A.sub.6 that has the largest number in any one of Formula 2-1 to Formula 2-19; preferably, in Formula 2-1 to Formula 2-19, at least one of X.sub.1 to X.sub.n is selected from N, wherein the X.sub.n corresponds to one of X.sub.1 to X.sub.7 that has the largest number in any one of Formula 2-1 to Formula 2-19; more preferably, X.sub.2 is N.

    16. The electroluminescent device according to claim 14, wherein in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are each independently selected from CR.sub.x, X.sub.3 to X.sub.7 are each independently selected from CR.sub.i, and A.sub.1 to A.sub.6 are each independently selected from CR.sub.ii; adjacent substituents R.sub.x, R.sub.i, R.sub.ii can be optionally joined to form a ring; preferably, R.sub.x, R.sub.i and R.sub.ii are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, cyano and combinations thereof, more preferably, at least two or three of R.sub.x, R.sub.i and R.sub.ii are, at each occurrence identically or differently, selected from the group consisting of: deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, cyano and combinations thereof.

    17. The electroluminescent device according to claim 1, wherein in the second compound, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21: ##STR00191## wherein in Formula 2-20 and Formula 2-21, Y is selected from O or S; R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms and combinations thereof, R is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms and combinations thereof, preferably, at least one or two of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2 and R.sub.i3 and/or at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, R is selected from halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, more preferably, at least one or two of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2 and R.sub.i3 and/or at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof; R is selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    18. The electroluminescent device according to claim 17, wherein R.sub.i2 is selected from the group consisting of: deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof; R is selected from halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, preferably, R.sub.i2 is selected from the group consisting of: substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, R is selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    19. The electroluminescent device according to claim 17, wherein in Formula 2-20 and Formula 2-21, at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group consisting of: substituted or unsubstituted alkyl having 3 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms and combinations thereof, and preferably, at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group consisting of: substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 ring carbon atoms and combinations thereof.

    20. The electroluminescent device according to claim 1, wherein the L.sub.a is, at each occurrence identically or differently, selected from the group consisting of the following structures: ##STR00192## ##STR00193## ##STR00194## ##STR00195## ##STR00196## ##STR00197## ##STR00198## ##STR00199## ##STR00200## ##STR00201## ##STR00202## ##STR00203## ##STR00204## ##STR00205## ##STR00206## ##STR00207## ##STR00208## ##STR00209## ##STR00210## ##STR00211## ##STR00212## ##STR00213## ##STR00214## ##STR00215## ##STR00216## ##STR00217## ##STR00218## ##STR00219## ##STR00220## ##STR00221## ##STR00222## ##STR00223## ##STR00224## ##STR00225## ##STR00226## wherein in the above structures, TMS represents trimethylsilyl; optionally, hydrogen in the structures of L.sub.a1 to L.sub.a168 can be partially or fully substituted with deuterium.

    21. The electroluminescent device according to claim 1, wherein the second compound has a general formula of M(L.sub.a).sub.m(L.sub.b).sub.n(L.sub.c).sub.q, wherein the metal M is selected from a metal with a relative atomic mass greater than 40, and L.sub.a, L.sub.b and L.sub.c are a first ligand, a second ligand and a third ligand of the complex, respectively; m is 1, 2 or 3, n is 0, 1 or 2, q is 0, 1 or 2, and m+n+q equals to an oxidation state of the metal M; wherein when m is greater than 1, a plurality of L.sub.a are identical or different; when n is 2, two L.sub.b are identical or different; when q is 2, two L.sub.c are identical or different; L.sub.a, L.sub.b and L.sub.c can be optionally joined to form a multidentate ligand; L.sub.b and L.sub.c are, at each occurrence identically or differently, selected from the group consisting of the following structures: ##STR00227## wherein R.sub.a, R.sub.b and R.sub.c represent, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; X.sub.b is, at each occurrence identically or differently, selected from the group consisting of: O, S, Se, NR.sub.N1 and CR.sub.C1R.sub.C2; X.sub.c and X.sub.d are, at each occurrence identically or differently, selected from the group consisting of: O, S, Se and NR.sub.N2, R.sub.a, R.sub.b, R.sub.c, R.sub.N1, R.sub.N2, R.sub.C1 and R.sub.c2 are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.a, R.sub.b, R.sub.c, R.sub.N1, R.sub.N2, R.sub.C1 and R.sub.C2 can be optionally joined to form a ring.

    22. The electroluminescent device according to claim 21, wherein the metal M is selected from Ir, Rh, Re, Os, Pt, Au or Cu; preferably, M is selected from Ir or Pt; more preferably, M is Ir.

    23. The electroluminescent device according to claim 21, wherein L.sub.b is, at each occurrence identically or differently, selected from the group consisting of the following structures: ##STR00228## ##STR00229## ##STR00230## ##STR00231## ##STR00232## ##STR00233## ##STR00234## ##STR00235## ##STR00236## ##STR00237## ##STR00238## ##STR00239## ##STR00240## ##STR00241## ##STR00242## ##STR00243## ##STR00244## ##STR00245## ##STR00246## ##STR00247## ##STR00248## ##STR00249## ##STR00250## ##STR00251## ##STR00252## ##STR00253## ##STR00254## ##STR00255## ##STR00256## ##STR00257## ##STR00258## ##STR00259## ##STR00260## ##STR00261## ##STR00262## ##STR00263## ##STR00264## ##STR00265## ##STR00266## ##STR00267## ##STR00268## ##STR00269## ##STR00270## ##STR00271## ##STR00272## ##STR00273## ##STR00274## ##STR00275## ##STR00276## ##STR00277## ##STR00278## ##STR00279## ##STR00280## ##STR00281## ##STR00282## ##STR00283## ##STR00284## ##STR00285## ##STR00286## ##STR00287## ##STR00288## ##STR00289## ##STR00290## ##STR00291## ##STR00292## wherein L.sub.c is, at each occurrence identically or differently, selected from the group consisting of the following structures: ##STR00293## ##STR00294## ##STR00295## ##STR00296## ##STR00297## ##STR00298## ##STR00299## ##STR00300## ##STR00301## ##STR00302## ##STR00303## ##STR00304## ##STR00305## ##STR00306## ##STR00307## ##STR00308## ##STR00309## ##STR00310## ##STR00311## ##STR00312## ##STR00313## ##STR00314## ##STR00315## ##STR00316## ##STR00317## ##STR00318## ##STR00319## ##STR00320## ##STR00321## ##STR00322## ##STR00323## ##STR00324## ##STR00325## ##STR00326## ##STR00327## ##STR00328## ##STR00329## ##STR00330## ##STR00331## ##STR00332## ##STR00333##

    24. The electroluminescent device according to claim 23, wherein the second compound is an Ir complex and has a structure represented by any one of Ir(L.sub.a)(L.sub.b)(L.sub.c), Ir(L.sub.a).sub.2(L.sub.b), Ir(L.sub.a).sub.2(L.sub.c) and Ir(L.sub.a)(L.sub.c).sub.2; when the second compound has a structure of Ir(L.sub.a)(L.sub.b)(L.sub.c), L.sub.a is selected from any one of the group consisting of L.sub.a1 to L.sub.a168, L.sub.b is selected from any one of the group consisting of L.sub.b1 to L.sub.b322, and L.sub.c is selected from any one of the group consisting of L.sub.c1 to L.sub.c231; when the second compound has a structure of Ir(L.sub.a).sub.2L.sub.b, L.sub.a is selected from any one or any two of the group consisting of L.sub.a1 to L.sub.a168, and L.sub.b is selected from any one of the group consisting of L.sub.b1 to L.sub.b322; when the second compound has a structure of Ir(L.sub.a).sub.2(L.sub.c), L.sub.a is selected from any one or any two of the group consisting of L.sub.a1 to L.sub.a168, and L.sub.c is selected from any one of the group consisting of L.sub.c1 to L.sub.c231; when the second compound has a structure of Ir(L.sub.a)(L.sub.c).sub.2, L.sub.a is selected from any one of the group consisting of L.sub.a1 to L.sub.a168, and L.sub.c is selected from any one or any two of the group consisting of L.sub.c1 to L.sub.c231; preferably, the second compound is selected from the group consisting of the following structures: ##STR00334## ##STR00335## ##STR00336## ##STR00337## ##STR00338## ##STR00339## ##STR00340## ##STR00341## ##STR00342## ##STR00343## ##STR00344## ##STR00345## ##STR00346## ##STR00347## ##STR00348## ##STR00349## ##STR00350## ##STR00351## ##STR00352## ##STR00353## ##STR00354## ##STR00355## ##STR00356## ##STR00357## ##STR00358## ##STR00359## ##STR00360## ##STR00361## ##STR00362## ##STR00363## ##STR00364## ##STR00365## ##STR00366## ##STR00367## ##STR00368##

    25. The electroluminescent device according to claim 1, wherein the organic layer is a light-emitting layer, the first compound is a host material, and the second compound is a light-emitting material.

    26. The electroluminescent device according to claim 25, wherein the device emits red light or white light.

    27. A display assembly, comprising the electroluminescent device according to claim 1.

    28. A compound combination, comprising at least a first compound and a second compound; wherein the first compound has a structure of H-L-E, wherein the H has a structure represented by Formula A: ##STR00369## wherein in Formula A, Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N, Z.sub.4 and Z.sub.5 are, at each occurrence identically or differently, selected from CR.sub.z2, and two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring; L is selected from a single bond, substituted or unsubstituted arylene having 6 to 30 carbon atoms, substituted or unsubstituted heteroarylene having 3 to 30 carbon atoms or a combination thereof, E is selected from substituted or unsubstituted aryl having 6 to 30 carbon atoms or substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms; R.sub.z1 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, R.sub.z2 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.z1, R.sub.z2 can be optionally joined to form a ring; wherein the second compound is a metal complex, wherein the metal is selected from a metal with a relative atomic mass greater than 40, and the metal complex comprises a ligand L.sub.a which has a structure represented by Formula C: ##STR00370## wherein in Formula C, the ring A and the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 30 carbon atoms or a heteroaromatic ring having 3 to 30 carbon atoms; R.sub.i represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; and R.sub.ii represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; Y is selected from SiR.sub.yR.sub.y, GeR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se; when two R.sub.y are present, the two R.sub.y may be identical or different; X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N; R, R.sub.i, R.sub.ii, R.sub.x and R.sub.y are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and adjacent substituents R.sub.i, R.sub.x, R.sub.y, R and R.sub.ii can be optionally joined to form a ring.

    Description

    BRIEF DESCRIPTION OF DRAWINGS

    [0048] FIG. 1 is a schematic diagram of an organic light-emitting apparatus that may include an electroluminescent device disclosed herein.

    [0049] FIG. 2 is a schematic diagram of another organic light-emitting apparatus that may include an electroluminescent device disclosed herein.

    DETAILED DESCRIPTION

    [0050] OLEDs can be fabricated on various types of substrates such as glass, plastic, and metal foil. FIG. 1 schematically shows an organic light-emitting device 100 without limitation. The figures are not necessarily drawn to scale. Some of the layers in the figures can also be omitted as needed. Device 100 may include a substrate 101, an anode 110, a hole injection layer 120, a hole transport layer 130, an electron blocking layer 140, an emissive layer 150, a hole blocking layer 160, an electron transport layer 170, an electron injection layer 180 and a cathode 190. Device 100 may be fabricated by depositing the layers described in order. The properties and functions of these various layers, as well as example materials, are described in more detail in U.S. Pat. No. 7,279,704 at cols. 6-10, the contents of which are incorporated by reference herein in its entirety.

    [0051] More examples for each of these layers are available. For example, a flexible and transparent substrate-anode combination is disclosed in U.S. Pat. No. 5,844,363, which is incorporated by reference herein in its entirety. An example of a p-doped hole transport layer is m-MTDATA doped with F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference herein in its entirety. Examples of host materials are disclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated by reference herein in its entirety. An example of an n-doped electron transport layer is BPhen doped with Li at a molar ratio of 1:1, as disclosed in U.S. Patent Application Publication No. 2003/0230980, which is incorporated by reference herein in its entirety. U.S. Pat. Nos. 5,703,436 and 5,707,745, which are incorporated by reference herein in their entireties, disclose examples of cathodes including composite cathodes having a thin layer of metal such as Mg:Ag with an overlying transparent, electrically-conductive, sputter-deposited ITO layer. The theory and use of blocking layers are described in more detail in U.S. Pat. No. 6,097,147 and U.S. Patent Application Publication No. 2003/0230980, which are incorporated by reference herein in their entireties. Examples of injection layers are provided in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference herein in its entirety. A description of protective layers may be found in U.S. Patent Application Publication No. 2004/0174116, which is incorporated by reference herein in its entirety.

    [0052] The layered structure described above is provided by way of non-limiting examples. Functional OLEDs may be achieved by combining the various layers described in different ways, or layers may be omitted entirely. It may also include other layers not specifically described. Within each layer, a single material or a mixture of multiple materials can be used to achieve optimum performance. Any functional layer may include several sublayers. For example, the emissive layer may have two layers of different emitting materials to achieve desired emission spectrum.

    [0053] In one embodiment, an OLED may be described as having an “organic layer” disposed between a cathode and an anode. This organic layer may include a single layer or multiple layers.

    [0054] An OLED can be encapsulated by a barrier layer. FIG. 2 schematically shows an organic light emitting device 200 without limitation. FIG. 2 differs from FIG. 1 in that the organic light emitting device include a barrier layer 102, which is above the cathode 190, to protect it from harmful species from the environment such as moisture and oxygen. Any material that can provide the barrier function can be used as the barrier layer such as glass or organic-inorganic hybrid layers. The barrier layer should be placed directly or indirectly outside of the OLED device. Multilayer thin film encapsulation was described in U.S. Pat. No. 7,968,146, which is incorporated by reference herein in its entirety.

    [0055] Devices fabricated in accordance with embodiments of the present disclosure can be incorporated into a wide variety of consumer products that have one or more of the electronic component modules (or units) incorporated therein. Some examples of such consumer products include flat panel displays, monitors, medical monitors, televisions, billboards, lights for interior or exterior illumination and/or signaling, heads-up displays, fully or partially transparent displays, flexible displays, smart phones, tablets, phablets, wearable devices, smart watches, laptop computers, digital cameras, camcorders, viewfinders, micro-displays, 3-D displays, vehicles displays, and vehicle tail lights.

    [0056] The materials and structures described herein may be used in other organic electronic devices listed above.

    [0057] As used herein, “top” means furthest away from the substrate, while “bottom” means closest to the substrate. Where a first layer is described as “disposed over” a second layer, the first layer is disposed further away from the substrate. There may be other layers between the first and second layers, unless it is specified that the first layer is “in contact with” the second layer. For example, a cathode may be described as “disposed over” an anode, even though there are various organic layers in between.

    [0058] As used herein, “solution processible” means capable of being dissolved, dispersed, or transported in and/or deposited from a liquid medium, either in solution or suspension form.

    [0059] A ligand may be referred to as “photoactive” when it is believed that the ligand directly contributes to the photoactive properties of an emissive material. A ligand may be referred to as “ancillary” when it is believed that the ligand does not contribute to the photoactive properties of an emissive material, although an ancillary ligand may alter the properties of a photoactive ligand.

    [0060] It is believed that the internal quantum efficiency (IQE) of fluorescent OLEDs can exceed the 25% spin statistics limit through delayed fluorescence. As used herein, there are two types of delayed fluorescence, i.e. P-type delayed fluorescence and E-type delayed fluorescence. P-type delayed fluorescence is generated from triplet-triplet annihilation (TTA).

    [0061] On the other hand, E-type delayed fluorescence does not rely on the collision of two triplets, but rather on the transition between the triplet states and the singlet excited states. Compounds that are capable of generating E-type delayed fluorescence are required to have very small singlet-triplet gaps to convert between energy states. Thermal energy can activate the transition from the triplet state back to the singlet state. This type of delayed fluorescence is also known as thermally activated delayed fluorescence (TADF). A distinctive feature of TADF is that the delayed component increases as temperature rises. If the reverse intersystem crossing (RISC) rate is fast enough to minimize the non-radiative decay from the triplet state, the fraction of back populated singlet excited states can potentially reach 75%. The total singlet fraction can be 100%, far exceeding 25% of the spin statistics limit for electrically generated excitons.

    [0062] E-type delayed fluorescence characteristics can be found in an exciplex system or in a single compound. Without being bound by theory, it is believed that E-type delayed fluorescence requires the luminescent material to have a small singlet-triplet energy gap (ΔE.sub.S-T). Organic, non-metal containing, donor-acceptor luminescent materials may be able to achieve this. The emission in these materials is generally characterized as a donor-acceptor charge-transfer (CT) type emission. The spatial separation of the HOMO and LUMO in these donor-acceptor type compounds generally results in small ΔE.sub.S-T. These states may involve CT states. Generally, donor-acceptor luminescent materials are constructed by connecting an electron donor moiety such as amino- or carbazole-derivatives and an electron acceptor moiety such as N-containing six-membered aromatic rings.

    Definition of Terms of Substituents

    [0063] Halogen or halide—as used herein includes fluorine, chlorine, bromine, and iodine.

    [0064] Alkyl—as used herein includes both straight and branched chain alkyl groups. Alkyl may be alkyl having 1 to 20 carbon atoms, preferably alkyl having 1 to 12 carbon atoms, and more preferably alkyl having 1 to 6 carbon atoms. Examples of alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an s-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, a neopentyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 1-pentylhexyl group, a 1-butylpentyl group, a 1-heptyloctyl group, and a 3-methylpentyl group. Of the above, preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, a neopentyl group, and an n-hexyl group. Additionally, the alkyl group may be optionally substituted.

    [0065] Cycloalkyl—as used herein includes cyclic alkyl groups. The cycloalkyl groups may be those having 3 to 20 ring carbon atoms, preferably those having 4 to 10 carbon atoms. Examples of cycloalkyl include cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4,4-dimethylcylcohexyl, 1-adamantyl, 2-adamantyl, 1-norbornyl, 2-norbornyl, and the like. Of the above, preferred are cyclopentyl, cyclohexyl, 4-methylcyclohexyl, and 4,4-dimethylcylcohexyl. Additionally, the cycloalkyl group may be optionally substituted.

    [0066] Heteroalkyl—as used herein, includes a group formed by replacing one or more carbons in an alkyl chain with a hetero-atom(s) selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, a phosphorus atom, a silicon atom, a germanium atom, and a boron atom. Heteroalkyl may be those having 1 to 20 carbon atoms, preferably those having 1 to 10 carbon atoms, and more preferably those having 1 to 6 carbon atoms. Examples of heteroalkyl include methoxymethyl, ethoxymethyl, ethoxyethyl, methylthiomethyl, ethylthiomethyl, ethylthioethyl, methoxymethoxymethyl, ethoxymethoxymethyl, ethoxyethoxyethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, mercaptomethyl, mercaptoethyl, mercaptopropyl, aminomethyl, aminoethyl, aminopropyl, dimethylaminomethyl, trimethyl silyl, dimethyl ethyl silyl, dimethylisopropylsilyl, t-butyldimethyl silyl, tri ethyl silyl, triisopropylsilyl, trimethyl silylmethyl, trimethyl silyl ethyl, and trimethylsilylisopropyl. Additionally, the heteroalkyl group may be optionally substituted.

    [0067] Alkenyl—as used herein includes straight chain, branched chain, and cyclic alkene groups. Alkenyl may be those having 2 to 20 carbon atoms, preferably those having 2 to 10 carbon atoms. Examples of alkenyl include vinyl, propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butandienyl, 1-methylvinyl, styryl, 2,2-diphenylvinyl, 1,2-diphenylvinyl, 1-methylallyl, 1,1-dimethylallyl, 2-methylallyl, 1-phenylallyl, 2-phenylallyl, 3-phenylallyl, 3,3-diphenylallyl, 1,2-dimethylallyl, 1-phenyl-1-butenyl, 3-phenyl-1-butenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, cycloheptenyl, cycloheptatrienyl, cyclooctenyl, cyclooctatetraenyl, and norbornenyl. Additionally, the alkenyl group may be optionally substituted.

    [0068] Alkynyl—as used herein includes straight chain alkynyl groups. Alkynyl may be those having 2 to 20 carbon atoms, preferably those having 2 to 10 carbon atoms. Examples of alkynyl groups include ethynyl, propynyl, propargyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3,3-dimethyl-1-butynyl, 3-ethyl-3-methyl-1-pentynyl, 3,3-diisopropyl-1-pentynyl, phenylethynyl, phenylpropynyl, etc. Of the above, preferred are ethynyl, propynyl, propargyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, and phenylethynyl. Additionally, the alkynyl group may be optionally substituted.

    [0069] Aryl or an aromatic group—as used herein includes non-condensed and condensed systems. Aryl may be those having 6 to 30 carbon atoms, preferably those having 6 to 20 carbon atoms, and more preferably those having 6 to 12 carbon atoms. Examples of aryl groups include phenyl, biphenyl, terphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene, chrysene, perylene, and azulene, preferably phenyl, biphenyl, terphenyl, triphenylene, fluorene, and naphthalene. Examples of non-condensed aryl groups include phenyl, biphenyl-2-yl, biphenyl-3-yl, biphenyl-4-yl, p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl, m-terphenyl-2-yl, o-tolyl, m-tolyl, p-tolyl, p-(2-phenylpropyl)phenyl, 4′-methylbiphenylyl, 4″-t-butyl-p-terphenyl-4-yl, o-cumenyl, m-cumenyl, p-cumenyl, 2,3-xylyl, 3,4-xylyl, 2,5-xylyl, mesityl, and m-quarterphenyl. Additionally, the aryl group may be optionally substituted.

    [0070] Heterocyclic groups or heterocyclic ring—as used herein include non-aromatic cyclic groups. Non-aromatic heterocyclic groups include saturated heterocyclic groups having 3 to 20 ring atoms and unsaturated non-aromatic heterocyclic groups having 3 to 20 ring atoms, where at least one ring atom is selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, a silicon atom, a phosphorus atom, a germanium atom, and a boron atom. Preferred non-aromatic heterocyclic groups are those having 3 to 7 ring atoms, each of which includes at least one hetero-atom such as nitrogen, oxygen, silicon, or sulfur. Examples of non-aromatic heterocyclic groups include oxiranyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, dioxolanyl, dioxanyl, aziridinyl, dihydropyrrolyl, tetrahydropyrrolyl, piperidinyl, oxazolidinyl, morpholinyl, piperazinyl, oxepinyl, thiepinyl, azepinyl, and tetrahydrosilolyl. Additionally, the heterocyclic group may be optionally substituted.

    [0071] Heteroaryl—as used herein, includes non-condensed and condensed hetero-aromatic groups having 1 to 5 hetero-atoms, wherein at least one hetero-atom is selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, a silicon atom, a phosphorus atom, a germanium atom, and a boron atom. A hetero-aromatic group is also referred to as heteroaryl. Heteroaryl may be those having 3 to 30 carbon atoms, preferably those having 3 to 20 carbon atoms, and more preferably those having 3 to 12 carbon atoms. Suitable heteroaryl groups include dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoselenophene, carbazole, indolocarbazole, pyridoindole, pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole, indenoazine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine, benzofuropyridine, furodipyridine, benzothienopyridine, thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine, and aza-analogs thereof. Additionally, the heteroaryl group may be optionally substituted.

    [0072] Alkoxy—as used herein, is represented by —O-alkyl, —O-cycloalkyl, —O-heteroalkyl, or —O-heterocyclic group. Examples and preferred examples of alkyl, cycloalkyl, heteroalkyl, and heterocyclic groups are the same as those described above. Alkoxy groups may be those having 1 to 20 carbon atoms, preferably those having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, tetrahydrofuranyloxy, tetrahydropyranyloxy, methoxypropyloxy, ethoxyethyloxy, methoxymethyloxy, and ethoxymethyloxy. Additionally, the alkoxy group may be optionally substituted.

    [0073] Aryloxy—as used herein, is represented by —O-aryl or —O-heteroaryl. Examples and preferred examples of aryl and heteroaryl are the same as those described above. Aryloxy groups may be those having 6 to 30 carbon atoms, preferably those having 6 to 20 carbon atoms. Examples of aryloxy groups include phenoxy and biphenyloxy. Additionally, the aryloxy group may be optionally substituted.

    [0074] Arylalkyl—as used herein, contemplates alkyl substituted with an aryl group. Arylalkyl may be those having 7 to 30 carbon atoms, preferably those having 7 to 20 carbon atoms, and more preferably those having 7 to 13 carbon atoms. Examples of arylalkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylisopropyl, 2-phenylisopropyl, phenyl-t-butyl, alpha-naphthylmethyl, 1-alpha-naphthylethyl, 2-alpha-naphthylethyl, 1-alpha-naphthylisopropyl, 2-alpha-naphthylisopropyl, betanaphthylmethyl, 1-beta-naphthylethyl, 2-beta-naphthylethyl, 1-beta-naphthylisopropyl, 2-beta-naphthylisopropyl, p-methylbenzyl, m-methylbenzyl, o-methylbenzyl, p-chlorobenzyl, m-chlorobenzyl, o-chlorobenzyl, p-bromobenzyl, m-bromobenzyl, o-bromobenzyl, p-iodobenzyl, m-iodobenzyl, o-iodobenzyl, p-hydroxybenzyl, m-hydroxybenzyl, o-hydroxybenzyl, p-aminobenzyl, m-aminobenzyl, o-aminobenzyl, p-nitrobenzyl, m-nitrobenzyl, o-nitrobenzyl, p-cyanobenzyl, m-cyanobenzyl, o-cyanobenzyl, 1-hydroxy-2-phenylisopropyl, and 1-chloro-2-phenylisopropyl. Of the above, preferred are benzyl, p-cyanobenzyl, m-cyanobenzyl, o-cyanobenzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylisopropyl, and 2-phenylisopropyl. Additionally, the arylalkyl group may be optionally substituted.

    [0075] Alkylsilyl—as used herein, contemplates a silyl group substituted with an alkyl group.

    [0076] Alkylsilyl groups may be those having 3 to 20 carbon atoms, preferably those having 3 to 10 carbon atoms. Examples of alkylsilyl groups include trimethylsilyl, triethylsilyl, methyldiethylsilyl, ethyldimethylsilyl, tripropylsilyl, tributylsilyl, triisopropylsilyl, methyldiisopropylsilyl, dimethylisopropylsilyl, tri-t-butylsilyl, triisobutylsilyl, dimethyl t-butylsilyl, and methyldi-t-butylsilyl. Additionally, the alkylsilyl group may be optionally substituted.

    [0077] Arylsilyl—as used herein, contemplates a silyl group substituted with at least one aryl group. Arylsilyl groups may be those having 6 to 30 carbon atoms, preferably those having 8 to 20 carbon atoms. Examples of arylsilyl groups include triphenylsilyl, phenyldibiphenylylsilyl, diphenylbiphenylsilyl, phenyldiethylsilyl, diphenylethylsilyl, phenyldimethylsilyl, diphenylmethylsilyl, phenyldiisopropylsilyl, diphenylisopropylsilyl, diphenylbutylsilyl, diphenylisobutylsilyl, diphenyl t-butylsilyl. Additionally, the arylsilyl group may be optionally substituted.

    [0078] The term “aza” in azadibenzofuran, azadibenzothiophene, etc. means that one or more of the C—H groups in the respective aromatic fragment are replaced by a nitrogen atom. For example, azatriphenylene encompasses dibenzo[f,h]quinoxaline, dibenzo[f,h]quinoline and other analogs with two or more nitrogens in the ring system. One of ordinary skill in the art can readily envision other nitrogen analogs of the aza-derivatives described above, and all such analogues are intended to be encompassed by the terms as set forth herein.

    [0079] In the present disclosure, unless otherwise defined, when any term of the group consisting of substituted alkyl, substituted cycloalkyl, substituted heteroalkyl, substituted heterocyclic group, substituted arylalkyl, substituted alkoxy, substituted aryloxy, substituted alkenyl, substituted alkynyl, substituted aryl, substituted heteroaryl, substituted alkylsilyl, substituted arylsilyl, substituted amino group, substituted acyl, substituted carbonyl, substituted carboxylic acid group, substituted ester group, substituted sulfinyl, substituted sulfonyl and substituted phosphino is used, it means that any group of alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, alkenyl, alkynyl, aryl, heteroaryl, alkylsilyl, arylsilyl, amino group, acyl, carbonyl, carboxylic acid group, ester group, sulfinyl, sulfonyl and phosphino may be substituted with one or more groups selected from the group consisting of deuterium, a halogen, an unsubstituted alkyl group having 1 to 20 carbon atoms, an unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, an unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an unsubstituted heterocyclic group having 3 to 20 ring atoms, an unsubstituted arylalkyl group having 7 to 30 carbon atoms, an unsubstituted alkoxy group having 1 to 20 carbon atoms, an unsubstituted aryloxy group having 6 to 30 carbon atoms, an unsubstituted alkenyl group having 2 to 20 carbon atoms, an unsubstituted alkynyl group having 2 to 20 carbon atoms, an unsubstituted aryl group having 6 to 30 carbon atoms, an unsubstituted heteroaryl group having 3 to 30 carbon atoms, an unsubstituted alkylsilyl group having 3 to 20 carbon atoms, an unsubstituted arylsilyl group having 6 to 20 carbon atoms, an unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, a cyano group, an isocyano group, a hydroxyl group, a sulfanyl group, a sulfinyl group, a sulfonyl group and a phosphino group, and combinations thereof.

    [0080] It is to be understood that when a molecular fragment is described as being a substituent or otherwise attached to another moiety, its name may be written as if it were a fragment (e.g. phenyl, phenylene, naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g. benzene, naphthalene, dibenzofuran). As used herein, these different ways of designating a substituent or an attached fragment are considered to be equivalent.

    [0081] In the compounds mentioned in the present disclosure, the hydrogen atoms may be partially or fully replaced by deuterium. Other atoms such as carbon and nitrogen can also be replaced by their other stable isotopes. The replacement by other stable isotopes in the compounds may be preferred due to its enhancements of device efficiency and stability.

    [0082] In the compounds mentioned in the present disclosure, multiple substitutions refer to a range that includes di-substitutions, up to the maximum available substitutions. When a substitution in the compounds mentioned in the present disclosure represents multiple substitutions (including di, tri, tetra substitutions, etc.), that means the substituent may exist at a plurality of available substitution positions on its linking structure, the substituents present at a plurality of available substitution positions may be the same structure or different structures.

    [0083] In the compounds mentioned in the present disclosure, adjacent substituents in the compounds cannot connect to form a ring unless otherwise explicitly defined, for example, adjacent substituents can be optionally joined to form a ring. In the compounds mentioned in the present disclosure, adjacent substituents can be optionally joined to form a ring, including both the case where adjacent substituents can be joined to form a ring, and the case where adjacent substituents are not joined to form a ring. When adjacent substituents can be optionally joined to form a ring, the ring formed may be monocyclic or polycyclic, as well as alicyclic, heteroalicyclic, aromatic or heteroaromatic. In such expression, adjacent substituents may refer to substituents bonded to the same atom, substituents bonded to carbon atoms which are directly bonded to each other, or substituents bonded to carbon atoms which are more distant from each other. Preferably, adjacent substituents refer to substituents bonded to the same carbon atom and substituents bonded to carbon atoms which are directly bonded to each other.

    [0084] The expression that adjacent substituents can be optionally joined to form a ring is also intended to mean that two substituents bonded to the same carbon atom are joined to each other via a chemical bond to form a ring, which can be exemplified by the following formula:

    ##STR00006##

    [0085] The expression that adjacent substituents can be optionally joined to form a ring is also intended to mean that two substituents bonded to carbon atoms which are directly bonded to each other are joined to each other via a chemical bond to form a ring, which can be exemplified by the following formula:

    ##STR00007##

    [0086] Furthermore, the expression that adjacent substituents can be optionally joined to form a ring is also intended to mean that, in the case where one of the two substituents bonded to carbon atoms which are directly bonded to each other represents hydrogen, the second substituent is bonded at a position at which the hydrogen atom is bonded, thereby forming a ring. This is exemplified by the following formula:

    ##STR00008##

    [0087] According to an embodiment of the present disclosure, disclosed is an electroluminescent device comprising:

    [0088] an anode,

    [0089] a cathode, and

    [0090] an organic layer disposed between the anode and the cathode, wherein the organic layer comprises at least a first compound and a second compound;

    [0091] wherein the first compound has a structure of H-L-E, wherein the H has a structure represented by Formula A:

    ##STR00009##

    [0092] wherein in Formula A,

    [0093] Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N, Z.sub.4 and Z.sub.5 are, at each occurrence identically or differently, selected from CR.sub.z2, and two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring;

    [0094] L is selected from a single bond, substituted or unsubstituted arylene having 6 to 30 carbon atoms, substituted or unsubstituted heteroarylene having 3 to 30 carbon atoms or a combination thereof;

    [0095] E is selected from substituted or unsubstituted aryl having 6 to 30 carbon atoms or substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms;

    [0096] R.sub.z1 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof;

    [0097] R.sub.z2 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0098] adjacent substituents R.sub.z1, R.sub.z2 can be optionally joined to form a ring;

    [0099] wherein the second compound is a metal complex, wherein the metal is selected from a metal with a relative atomic mass greater than 40, and the metal complex comprises a ligand L.sub.a which has a structure represented by Formula C:

    ##STR00010##

    [0100] wherein in Formula C, the ring A and the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 30 carbon atoms or a heteroaromatic ring having 3 to 30 carbon atoms;

    [0101] R.sub.i represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; and R.sub.ii represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;

    [0102] Y is selected from SiR.sub.yR.sub.y, GeR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se;

    [0103] when two R.sub.y are present, the two R.sub.y may be identical or different;

    [0104] X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N;

    [0105] R, R.sub.i, R.sub.ii, R.sub.x and R.sub.y are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0106] adjacent substituents R.sub.i, R.sub.x, R.sub.y, R and R.sub.ii can be optionally joined to form a ring.

    [0107] In this embodiment, the expression that “adjacent substituents R.sub.z1, R.sub.z2 can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as adjacent substituents R.sub.z1 in Z.sub.1 to Z.sub.3, adjacent substituents R.sub.z1 in Z.sub.6 to Z.sub.8, substituent R.sub.z1 in Z.sub.3 and substituent R.sub.z2 in Z.sub.4, substituent R.sub.z1 in Z.sub.3 and substituent R.sub.z2 in Z.sub.5, substituent R.sub.z1 in Z.sub.6 and substituent R.sub.z2 in Z.sub.4, and substituent R.sub.z1 in Z.sub.6 and substituent R.sub.z2 in Z.sub.5, can be joined to form a ring. Obviously, it is possible that none of these groups of adjacent substituents are joined to form a ring.

    [0108] In the present disclosure, the expression that “adjacent substituents R.sub.i, R.sub.x, R.sub.y, R and R.sub.ii can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as two substituents R.sub.i, two substituents R.sub.ii, two substituents R.sub.y, two substituents R.sub.x, substituents R.sub.i and R.sub.x, substituents R and R.sub.y, and substituents R.sub.ii and R, can be joined to form a ring. Obviously, it is possible that none of these substituents are joined to form a ring.

    [0109] According to an embodiment of the present disclosure, wherein, in Formula A, the two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring, and the ring has at least six ring atoms.

    [0110] According to an embodiment of the present disclosure, wherein, in Formula A, the two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring, and the ring has at least seven ring atoms.

    [0111] According to an embodiment of the present disclosure, wherein, in the first compound, the H has a structure represented by any one of Formula A-1 to Formula A-8:

    ##STR00011##

    [0112] wherein in Formula A-1 to Formula A-8,

    [0113] Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N;

    [0114] Z.sub.h1 to Z.sub.h8 are, at each occurrence identically or differently, selected from CR.sub.zh or N;

    [0115] Z.sub.m is selected from CR.sub.zm or N;

    [0116] Z.sub.n is selected from CR.sub.znR.sub.zn, O, S or NR.sub.zn; wherein when Z.sub.n is selected from CR.sub.znR.sub.zn, two R.sub.zn may be identical or different;

    [0117] R.sub.z1, R.sub.zh, R.sub.zm and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0118] adjacent substituents R.sub.z1, R.sub.zh, R.sub.zm, R.sub.zn can be optionally joined to form a ring.

    [0119] In the present disclosure, the expression that “adjacent substituents R.sub.z1, R.sub.zh, R.sub.zm, R.sub.zn can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as adjacent substituents R.sub.z1 in Z.sub.1 to Z.sub.3, adjacent substituents R.sub.z1 in Z.sub.6 to Z.sub.8, adjacent substituents R.sub.zh, adjacent substituents R.sub.zh and R.sub.zm, adjacent substituents R.sub.zn, and adjacent substituents R.sub.zh and R.sub.zn, can be joined to form a ring. Obviously, it is possible that none of these groups of adjacent substituents are joined to form a ring.

    [0120] According to an embodiment of the present disclosure, wherein, in Formula A-1 to Formula A-8, R.sub.z1, R.sub.zh, R.sub.zm and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, cyano, isocyano, hydroxyl, a sulfanyl group and combinations thereof, and

    [0121] adjacent substituents R.sub.z1, R.sub.zh, R.sub.zm, R.sub.zn can be optionally joined to form a ring.

    [0122] According to an embodiment of the present disclosure, wherein, in the first compound, the H has a structure represented by any one of Formula A-1 to Formula A-8:

    ##STR00012##

    [0123] wherein in Formula A-1 to Formula A-8,

    [0124] Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1;

    [0125] Z.sub.h1 to Z.sub.h8 are, at each occurrence identically or differently, selected from CR.sub.zh or N;

    [0126] Z.sub.m is selected from N;

    [0127] Z.sub.n is selected from O, S or NR.sub.zn;

    [0128] R.sub.z1, R.sub.zh, and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0129] adjacent substituents R.sub.z1, R.sub.zh, R.sub.zn can be optionally joined to form a ring.

    [0130] In the present disclosure, the expression that “adjacent substituents R.sub.z1, R.sub.zh, R.sub.zn can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as adjacent substituents R.sub.z1 in Z.sub.1 to Z.sub.3, adjacent substituents R.sub.z1 in Z.sub.6 to Z.sub.8, adjacent substituents R.sub.zh, adjacent substituents R.sub.zn, and adjacent substituents R.sub.zh and R.sub.zn, can be joined to form a ring. Obviously, it is possible that none of these groups of adjacent substituents are joined to form a ring.

    [0131] According to an embodiment of the present disclosure, wherein, in the first compound, the H has a structure represented by any one of Formula A-1 to Formula A-8:

    ##STR00013## ##STR00014##

    [0132] wherein in Formula A-1 to Formula A-8,

    [0133] Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1;

    [0134] Z.sub.h1 to Z.sub.h8 are, at each occurrence identically or differently, selected from CR.sub.zh or N;

    [0135] Z.sub.m is selected from N;

    [0136] Z.sub.n is selected from O, S or NR.sub.zn;

    [0137] R.sub.z1, R.sub.zh and R.sub.zn are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, cyano, isocyano, hydroxyl, a sulfanyl group and combinations thereof, and

    [0138] adjacent substituents R.sub.z1, R.sub.zh, R.sub.zn can be optionally joined to form a ring.

    [0139] According to an embodiment of the present disclosure, wherein, in the first compound, the H is selected from the group consisting of the following structures:

    ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032##

    [0140] In this embodiment, “*” represents a position where the structure of H is joined to the L.

    [0141] According to an embodiment of the present disclosure, wherein, hydrogen in the structures of H-1 to H-76 can be partially or fully substituted with deuterium.

    [0142] According to an embodiment of the present disclosure, wherein, in the first compound, the E has a structure represented by Formula E-a or Formula E-b:

    ##STR00033##

    [0143] wherein in Formula E-a and Formula E-b,

    [0144] E.sub.1 to E.sub.14 are, at each occurrence identically or differently, selected from C, CR.sub.e or N;

    [0145] R.sub.e is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0146] adjacent substituents R.sub.e can be optionally joined to form a ring.

    [0147] In this embodiment, “custom-character” represents a position where the structure of E is joined to the L.

    [0148] In this embodiment, in Formula E-a, one of E.sub.1 to E.sub.6 is C, and the C is joined to the L; in Formula E-b, one of E.sub.7 to E.sub.14 is C, and the C is joined to the L.

    [0149] In this embodiment, the expression that “adjacent substituents R.sub.e can be optionally joined to form a ring” is intended to mean that any adjacent substituents R.sub.e can be joined to form a ring. Obviously, it is possible that any adjacent substituents R.sub.e are not joined to form a ring.

    [0150] According to an embodiment of the present disclosure, wherein, in Formula E-a, at least two of E.sub.1 to E.sub.6 are N; in Formula E-b, at least two of E.sub.7 to E.sub.14 are N.

    [0151] According to an embodiment of the present disclosure, wherein, in Formula E-a, three of E.sub.1 to E.sub.6 are N; in Formula E-b, two of E.sub.7 to E.sub.10 are N.

    [0152] According to an embodiment of the present disclosure, wherein, in the first compound, the E has a structure represented by any one of Formula E-1 to Formula E-10:

    ##STR00034## ##STR00035##

    [0153] R.sub.A represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;

    [0154] V is selected from O, S or Se;

    [0155] R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0156] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0157] In the present disclosure, the expression that “adjacent substituents R.sub.A can be optionally joined to form a ring” is intended to mean that any adjacent substituents R.sub.A can be joined to form a ring. Obviously, it is possible that any adjacent substituents R.sub.A are not joined to form a ring.

    [0158] In this embodiment, “custom-character” represents a position where the structure of E is joined to the L.

    [0159] According to an embodiment of the present disclosure, wherein, in the first compound, the E has a structure represented by any one of Formula E-11 to Formula E-21:

    ##STR00036## ##STR00037##

    [0160] R.sub.A represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;

    [0161] V is selected from O, S or Se;

    [0162] R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms and combinations thereof, and

    [0163] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0164] In this embodiment, “custom-character” represents a position where the structure of E is joined to the L.

    [0165] According to an embodiment of the present disclosure, wherein, in Formula E-1 to Formula E-21, R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, cyano, hydroxyl, a sulfanyl group, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, and

    [0166] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0167] According to an embodiment of the present disclosure, wherein, in Formula E-1 to Formula E-21, R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, fluorine, cyano, hydroxyl, a sulfanyl group, methyl, trideuteriomethyl, vinyl, phenyl, biphenyl, naphthyl, 4-cyanophenyl, dibenzofuranyl, dibenzothienyl, triphenylene, carbazolyl, 9-phenylcarbazolyl, 9,9-dimethylfluorenyl, pyridyl, phenylpyridyl and combinations thereof, and

    [0168] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0169] According to an embodiment of the present disclosure, wherein, in Formula E-1 to Formula E-21, at least one R.sub.A is present, and the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, halogen, cyano, hydroxyl, a sulfanyl group, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, and

    [0170] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0171] According to an embodiment of the present disclosure, wherein, in Formula E-1 to Formula E-21, at least one R.sub.A is present, and the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, halogen, cyano, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms and combinations thereof, and

    [0172] adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0173] According to an embodiment of the present disclosure, wherein, in Formula E-1 to Formula E-21, at least one R.sub.A is present, and the at least one R.sub.A is, at each occurrence identically or differently, selected from the group consisting of: deuterium, fluorine, cyano, methyl, trideuteriomethyl, phenyl, biphenyl, naphthyl, 4-cyanophenyl, dibenzofuranyl, dibenzothienyl, triphenylene, carbazolyl, 9-phenylcarbazolyl, 9,9-dimethylfluorenyl, pyridyl, phenylpyridyl and combinations thereof, and adjacent substituents R.sub.A can be optionally joined to form a ring.

    [0174] According to an embodiment of the present disclosure, wherein, in the first compound, the E is selected from the group consisting of the following structures:

    ##STR00038## ##STR00039## ##STR00040## ##STR00041## ##STR00042## ##STR00043## ##STR00044## ##STR00045##

    [0175] wherein “custom-character” represents a position where the structure of E is joined to the L.

    [0176] According to an embodiment of the present disclosure, wherein, the L is selected from the group consisting of: a single bond, phenylene, naphthylene, biphenylene, terphenylene, triphenylenylene, pyridylene, dibenzothienylene, dibenzofuranylene and thienylene.

    [0177] According to an embodiment of the present disclosure, wherein, the L is selected from the group consisting of the following structures:

    ##STR00046## ##STR00047## ##STR00048##

    [0178] wherein “*” represents a position where the structure of L is joined to the H, and “custom-character” represents a position where the structure of L is joined to the E.

    [0179] According to an embodiment of the present disclosure, wherein, hydrogen in the structures of L-1 to L-22 can be partially or fully substituted with deuterium.

    [0180] According to an embodiment of the present disclosure, wherein, the first compound has the structure of H-L-E, wherein the H is selected from any one of the group consisting of H-1 to H-76, the L is selected from any one of the group consisting of L-0 to L-22, and the E is selected from any one of the group consisting of E-1 to E-38. Optionally, hydrogen in the structure of the first compound can be partially or fully substituted with deuterium.

    [0181] According to an embodiment of the present disclosure, wherein, the first compound is selected from the group consisting of Compound 1-1 to Compound 1-249, wherein the specific structures of Compound 1-1 to Compound 1-249 are referred to claim 12.

    [0182] According to an embodiment of the present disclosure, wherein, hydrogen in Compound 1-1 to Compound 1-249 can be partially or fully substituted with deuterium.

    [0183] According to an embodiment of the present disclosure, wherein, in the second compound, in Formula C, the ring A and/or the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 18 carbon atoms or a heteroaromatic ring having 3 to 18 carbon atoms.

    [0184] According to an embodiment of the present disclosure, wherein, in the second compound, in Formula C, the ring A and/or the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 10 carbon atoms or a heteroaromatic ring having 3 to 10 carbon atoms.

    [0185] According to an embodiment of the present disclosure, wherein, in the second compound, the L.sub.a has a structure represented by any one of Formula 2-1 to Formula 2-19:

    ##STR00049## ##STR00050## ##STR00051## ##STR00052## ##STR00053##

    [0186] wherein

    [0187] in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N, X.sub.3 to X.sub.7 are, at each occurrence identically or differently, selected from CR.sub.i or N, and A.sub.1 to A.sub.6 are, at each occurrence identically or differently, selected from CR.sub.ii or N;

    [0188] Z is, at each occurrence identically or differently, selected from CR.sub.iiiR.sub.iii, SiR.sub.iiiR.sub.iii, PR.sub.iii, O, S or NR.sub.iii; wherein when two R.sub.iii are present, the two R.sub.iii are identical or different;

    [0189] Y is selected from SiR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se; wherein when two R.sub.y are present, the two R.sub.y are identical or different;

    [0190] R, R.sub.x, R.sub.y, R.sub.i, R.sub.ii and R.sub.iii are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0191] adjacent substituents R, R.sub.x, R.sub.y, R.sub.i, R.sub.ii and R.sub.iii can be optionally joined to form a ring.

    [0192] In the present disclosure, the expression that “adjacent substituents R, R.sub.x, R.sub.y, R.sub.i, R.sub.ii and R.sub.iii can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as two substituents R.sub.i, two substituents R.sub.ii, two substituents R.sub.x, two substituents R.sub.y, two substituents R.sub.iii, substituents R.sub.i and R.sub.x, substituents R.sub.ii and R.sub.iii, substituents R and R.sub.y, substituents R.sub.y and R.sub.iii, substituents R.sub.x and R.sub.iii, and substituents R and R.sub.iii, can be joined to form a ring. Obviously, it is possible that none of these substituents are joined to form a ring.

    [0193] According to an embodiment of the present disclosure, L.sub.a is selected from a structure represented by any one of Formula 2-1, Formula 2-5, Formula 2-8, Formula 2-10, Formula 2-11 or Formula 2-12.

    [0194] According to an embodiment of the present disclosure, L.sub.a is selected from a structure represented by Formula 2-1.

    [0195] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, at least one of X.sub.1 to X.sub.n and/or A.sub.1 to A.sub.m is selected from N, wherein the X.sub.n corresponds to one of X.sub.1 to X.sub.7 that has the largest number in any one of Formula 2-1 to Formula 2-19, and the A.sub.m corresponds to one of A.sub.1 to A.sub.6 that has the largest number in any one of Formula 2-1 to Formula 2-19. For example, in Formula 2-1, the X.sub.n corresponds to X.sub.5 of X.sub.1 to X.sub.7 that has the largest number in Formula 2-1, and the A.sub.m corresponds to A.sub.4 of A.sub.1 to A.sub.6 that has the largest number in Formula 2-1, that is, in Formula 2-1, at least one of X.sub.1 to X.sub.5 and/or A.sub.1 to A.sub.4 is selected from N. In another example, in Formula 2-12, the X.sub.n corresponds to X.sub.3 of X.sub.1 to X.sub.7 that has the largest number in Formula 2-12, and the A.sub.m corresponds to A.sub.4 of A.sub.1 to A.sub.6 that has the largest number in Formula 2-12, that is, in Formula 2-12, at least one of X.sub.1 to X.sub.3 and/or A.sub.1 to A.sub.4 is selected from N.

    [0196] According to an embodiment of the present disclosure, in Formula 2-1 to Formula 2-19, at least one of X.sub.1 to X.sub.n is selected from N, wherein the X.sub.n corresponds to one of X.sub.1 to X.sub.7 that has the largest number in any one of Formula 2-1 to Formula 2-19.

    [0197] According to an embodiment of the present disclosure, in Formula 2-1 to Formula 2-19, X.sub.2 is N.

    [0198] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are each independently selected from CR.sub.x, X.sub.3 to X.sub.7 are each independently selected from CR.sub.i, A.sub.1 to A.sub.6 are each independently selected from CR.sub.ii, and adjacent substituents R.sub.x, R.sub.i, R.sub.ii can be optionally joined to form a ring.

    [0199] In this embodiment, the expression that “adjacent substituents R.sub.x, R.sub.i, R.sub.ii can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as two substituents R.sub.i, two substituents R.sub.ii, two substituents R.sub.x, and substituents R.sub.i and R.sub.x, can be joined to form a ring. Obviously, it is possible that none of these substituents are joined to form a ring.

    [0200] According to an embodiment of the present disclosure, the R.sub.x, R.sub.i and R.sub.ii are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, cyano and combinations thereof.

    [0201] According to an embodiment of the present disclosure, at least two or three of the R.sub.x, R.sub.i and R.sub.ii are, at each occurrence identically or differently, selected from the group consisting of: [0202] deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, cyano and combinations thereof.

    [0203] In this embodiment, the expression that at least two or three of R.sub.x, R.sub.i and R.sub.ii are, at each occurrence identically or differently, selected from the group of substituents is intended to mean that at least two or three substituents in the group consisting of two substituents R.sub.x, all substituents R.sub.i and all substituents R.sub.ii are, at each occurrence identically or differently, selected from the group of substituents.

    [0204] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-11, X.sub.4 and/or X.sub.5 is selected from CR.sub.i, and in Formula 2-12 to Formula 2-19, X.sub.3 is selected from CR.sub.i; and

    [0205] the R.sub.i is, at each occurrence identically or differently, selected from hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0206] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-11, X.sub.4 and/or X.sub.5 is selected from CR.sub.i, and in Formula 2-12 to Formula 2-19, X.sub.3 is selected from CR.sub.i; and the R.sub.i is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, fluorine, methyl, ethyl, isopropyl, isobutyl, t-butyl, neopentyl, cyclopentyl, cyclopentylmethyl, cyclohexyl, norbornyl, adamantyl, trimethylsilyl, isopropyldimethylsilyl, phenyldimethylsilyl, trifluoromethyl, cyano and combinations thereof.

    [0207] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, the R is selected from hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0208] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, the R is selected from hydrogen, deuterium, fluorine, methyl, ethyl, isopropyl, isobutyl, t-butyl, cyclopentyl, cyclopentylmethyl, cyclohexyl, neopentyl, deuterated methyl, deuterated ethyl, deuterated isopropyl, deuterated isobutyl, deuterated t-butyl, deuterated cyclopentyl, deuterated cyclopentylmethyl, deuterated cyclohexyl, deuterated neopentyl, trimethylsilyl or a combination thereof.

    [0209] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, Y is selected from O or S.

    [0210] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, Y is O.

    [0211] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are each independently selected from CR.sub.x.

    [0212] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, X.sub.1 and X.sub.2 are each independently selected from CR.sub.x, wherein the R.sub.x is, at each occurrence identically or differently, selected from hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0213] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, X.sub.1 is selected from CR.sub.x, and X.sub.2 is N.

    [0214] According to an embodiment of the present disclosure, wherein, in Formula 2-1 to Formula 2-19, X.sub.1 is selected from CR.sub.x, and X.sub.2 is N, wherein the R.sub.x is selected from hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0215] According to an embodiment of the present disclosure, wherein, in the second compound, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21:

    ##STR00054##

    [0216] wherein in Formula 2-20 and Formula 2-21,

    [0217] Y is selected from O or S;

    [0218] R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms and combinations thereof;

    [0219] R is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms and combinations thereof.

    [0220] According to an embodiment of the present disclosure, wherein, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21:

    ##STR00055##

    [0221] wherein in Formula 2-20 and Formula 2-21,

    [0222] Y is selected from O or S; and

    [0223] at least one or two of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2 and R.sub.i3 and/or at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, R is selected from halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0224] According to an embodiment of the present disclosure, wherein, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21:

    ##STR00056##

    [0225] wherein in Formula 2-20 and Formula 2-21,

    [0226] Y is selected from O or S; and

    [0227] at least one or two of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2 and R.sub.i3 and/or at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof; R is selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0228] According to an embodiment of the present disclosure, wherein, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21:

    ##STR00057##

    [0229] wherein in Formula 2-20 and Formula 2-21,

    [0230] Y is selected from O or S;

    [0231] R.sub.i2 is selected from the group consisting of: deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and

    [0232] R is selected from halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0233] According to an embodiment of the present disclosure, wherein, the ligand L.sub.a has a structure represented by Formula 2-20 or Formula 2-21:

    ##STR00058##

    [0234] wherein in Formula 2-20 and Formula 2-21,

    [0235] Y is selected from O or S;

    [0236] R.sub.i2 is selected from the group consisting of: substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and

    [0237] R is selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof, and at least one or two of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 are, at each occurrence identically or differently, selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms or a combination thereof.

    [0238] According to an embodiment of the present disclosure, wherein, in Formula 2-20 and Formula 2-21, at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group consisting of: substituted or unsubstituted alkyl having 3 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms and combinations thereof.

    [0239] In this embodiment, the expression that at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group of substituents is intended to mean that at least one of R.sub.x1 and R.sub.x2 is, at each occurrence identically or differently, selected from the group of substituents and/or that at least one of R.sub.i1, R.sub.i2 and R.sub.i3 is, at each occurrence identically or differently, selected from the group of substituents and/or that at least one of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 is, at each occurrence identically or differently, selected from the group of substituents and/or that R is selected from the group of substituents.

    [0240] According to an embodiment of the present disclosure, wherein, in Formula 2-20 and Formula 2-21, at least one of R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3 and R is, at each occurrence identically or differently, selected from the group consisting of: substituted or unsubstituted alkyl having 3 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms and combinations thereof.

    [0241] In this embodiment, the expression that at least one of R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3 and R is, at each occurrence identically or differently, selected from the group of substituents is intended to mean that at least one of R.sub.i2 and R.sub.i3 is, at each occurrence identically or differently, selected from the group of substituents and/or that at least one of R.sub.ii1, R.sub.ii2 and R.sub.ii3 is, at each occurrence identically or differently, selected from the group of substituents and/or that R is selected from the group of substituents.

    [0242] According to an embodiment of the present disclosure, wherein, in Formula 2-20 and Formula 2-21, at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group consisting of: substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 ring carbon atoms and combinations thereof.

    [0243] In this embodiment, the expression that at least one of R.sub.x1, R.sub.x2, R.sub.i1, R.sub.i2, R.sub.i3, R.sub.ii1, R.sub.ii2, R.sub.ii3, R.sub.ii4 and R is, at each occurrence identically or differently, selected from the group of substituents is intended to mean that at least one of R.sub.x1 and R.sub.x2 is, at each occurrence identically or differently, selected from the group of substituents and/or that at least one of R.sub.i1, R.sub.i2 and R.sub.i3 is, at each occurrence identically or differently, selected from the group of substituents and/or that at least one of R.sub.ii1, R.sub.ii2, R.sub.ii3 and R.sub.ii4 is, at each occurrence identically or differently, selected from the group of substituents and/or that R is selected from the group of substituents.

    [0244] According to an embodiment of the present disclosure, wherein, the L.sub.a is selected from the group consisting of L.sub.a1 to L.sub.a188:

    ##STR00059## ##STR00060## ##STR00061## ##STR00062## ##STR00063## ##STR00064## ##STR00065## ##STR00066## ##STR00067## ##STR00068## ##STR00069## ##STR00070## ##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075## ##STR00076## ##STR00077## ##STR00078## ##STR00079## ##STR00080## ##STR00081## ##STR00082## ##STR00083## ##STR00084## ##STR00085## ##STR00086## ##STR00087## ##STR00088## ##STR00089## ##STR00090## ##STR00091## ##STR00092## ##STR00093## ##STR00094## ##STR00095## ##STR00096## ##STR00097## ##STR00098## ##STR00099##

    [0245] wherein in the above structures, TMS represents trimethylsilyl.

    [0246] According to an embodiment of the present disclosure, wherein, hydrogen in the structures of L.sub.a1 to L.sub.a188 can be partially or fully substituted with deuterium.

    [0247] According to an embodiment of the present disclosure, wherein, the second compound has a structure of M(L.sub.a).sub.m(L.sub.b).sub.n(L.sub.c).sub.q; wherein

    [0248] the metal M is selected from a metal with a relative atomic mass greater than 40; L.sub.a, L.sub.b and L.sub.c, are a first ligand, a second ligand and a third ligand of the complex, respectively; m is 1, 2 or 3, n is 0, 1 or 2, q is 0, 1 or 2, and m+n+q equals to an oxidation state of the metal M; wherein when m is greater than 1, a plurality of L.sub.a are identical or different; when n is 2, two L.sub.b are identical or different; when q is 2, two L.sub.c are identical or different;

    [0249] L.sub.a, L.sub.b and L.sub.c can be optionally joined to form a multidentate ligand; for example, L.sub.a, L.sub.b and L.sub.c can be optionally joined to form a tetradentate ligand or a hexadentate ligand; it is possible that L.sub.a, L.sub.b and L.sub.c are not joined so that no multidentate ligand is formed;

    [0250] L.sub.b and L.sub.c are, at each occurrence identically or differently, selected from the group consisting of the following structures:

    ##STR00100##

    [0251] wherein R.sub.a, R.sub.b and R.sub.c represent, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;

    [0252] X.sub.b is, at each occurrence identically or differently, selected from the group consisting of: O, S, Se, NR.sub.N1 and CR.sub.C1R.sub.C2;

    [0253] X.sub.c and X.sub.d are, at each occurrence identically or differently, selected from the group consisting of: O, S, Se and NR.sub.N2;

    [0254] R.sub.a, R.sub.b, R.sub.c, R.sub.N1, R.sub.N2, R.sub.C1 and R.sub.C2 are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof; and

    [0255] adjacent substituents R.sub.a, R.sub.b, R.sub.c, R.sub.N1, R.sub.N2, R.sub.C1 and R.sub.C2 can be optionally joined to form a ring.

    [0256] In this embodiment, the expression that “adjacent substituents R.sub.a, R.sub.b, R.sub.c, R.sub.N1, R.sub.N2, R.sub.C1 and R.sub.C2 can be optionally joined to form a ring” is intended to mean that any one or more of groups of adjacent substituents, such as two substituents R.sub.a, two substituents R.sub.b, two substituents R.sub.c, substituents R.sub.a and R.sub.b, substituents R.sub.a and R.sub.c, substituents R.sub.b and R.sub.c, substituents R.sub.a and R.sub.N1, substituents R.sub.b and R.sub.N1, substituents R.sub.a and R.sub.C1, substituents R.sub.a and R.sub.C2, substituents R.sub.b and R.sub.C1, substituents R.sub.b and R.sub.c2, substituents R.sub.a and R.sub.N2, substituents R.sub.b and R.sub.N2, and substituents R.sub.C1 and R.sub.C2, can be joined to form a ring. Obviously, it is possible that none of these substituents are joined to form a ring.

    [0257] In this embodiment, the expression that “L.sub.a, L.sub.b and L.sub.c can be optionally joined to form a multidentate ligand” is intended to mean that any two or three of L.sub.a, L.sub.b and L.sub.c can be joined to form a tetradentate ligand or a hexadentate ligand. Obviously, it is possible that none of L.sub.a, L.sub.b and L.sub.c are joined to form a multidentate ligand.

    [0258] According to an embodiment of the present disclosure, wherein, in the second compound, the metal M is selected from Ir, Rh, Re, Os, Pt, Au or Cu.

    [0259] According to an embodiment of the present disclosure, wherein, in the second compound, the metal M is selected from Ir, Pt or Os.

    [0260] According to an embodiment of the present disclosure, wherein, in the second compound, the metal M is Ir.

    [0261] According to an embodiment of the present disclosure, in the device, the second compound is an Ir complex and has a structure represented by any one of Ir(L.sub.a)(L.sub.b)(L.sub.c), Ir(L.sub.a).sub.2(L.sub.b), Ir(L.sub.a).sub.2(L.sub.c) or Ir(L.sub.a)(L.sub.c).sub.2.

    [0262] According to an embodiment of the present disclosure, wherein, L.sub.b is, at each occurrence identically or differently, selected from the following structure:

    ##STR00101##

    [0263] wherein R.sub.1 to R.sub.7 are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof.

    [0264] According to an embodiment of the present disclosure, wherein, L.sub.b is, at each occurrence identically or differently, selected from the following structure:

    ##STR00102##

    [0265] wherein at least one of R.sub.1 to R.sub.3 is selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms or a combination thereof; and/or at least one of R.sub.4 to R.sub.6 is substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms or a combination thereof.

    [0266] According to an embodiment of the present disclosure, wherein, L.sub.b is, at each occurrence identically or differently, selected from the following structure:

    ##STR00103##

    [0267] wherein at least two of R.sub.1 to R.sub.3 are selected from substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms or a combination thereof; and/or at least one of R.sub.4 to R.sub.6 is substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms or a combination thereof.

    [0268] According to an embodiment of the present disclosure, wherein, L.sub.b is, at each occurrence identically or differently, selected from the following structure:

    ##STR00104##

    [0269] wherein at least two of R.sub.1 to R.sub.3 are selected from substituted or unsubstituted alkyl having 2 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 2 to 20 carbon atoms or a combination thereof, and/or at least two of R.sub.4 to R.sub.6 are selected from substituted or unsubstituted alkyl having 2 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 2 to 20 carbon atoms or a combination thereof.

    [0270] According to an embodiment of the present disclosure, wherein, in the second compound, L.sub.b is, at each occurrence identically or differently, selected from the group consisting of L.sub.b1 to L.sub.b322, wherein the specific structures of L.sub.bl to L.sub.b322 are referred to claim 23.

    [0271] According to an embodiment of the present disclosure, wherein, in the second compound, L.sub.c is, at each occurrence identically or differently, selected from the group consisting of L.sub.c1 to L.sub.c231, wherein the specific structures of L.sub.c1 to L.sub.c231 are referred to claim 23.

    [0272] According to an embodiment of the present disclosure, in the device, the second compound is an Ir complex and has a structure represented by any one of Ir(L.sub.a)(L.sub.b)(L.sub.c), Ir(L.sub.a).sub.2(L.sub.b), Ir(L.sub.a).sub.2(L.sub.c) and Ir(L.sub.a)(L.sub.c).sub.2; when the second compound has a structure of Ir(L.sub.a)(L.sub.b)(L.sub.c), L.sub.a is selected from any one of the group consisting of L.sub.a1 to L.sub.a188, L.sub.b is selected from any one of the group consisting of L.sub.bl to L.sub.b322, and L.sub.c is selected from any one of the group consisting of L.sub.c1 to L.sub.c231; when the second compound has a structure of Ir(L.sub.a).sub.2L.sub.b, L.sub.a is selected from any one or any two of the group consisting of L.sub.a1 to L.sub.a188, and L.sub.b is selected from any one of the group consisting of L.sub.b1 to L.sub.b322; when the second compound has a structure of Ir(L.sub.a).sub.2(L.sub.c), L.sub.a is selected from any one or any two of the group consisting of L.sub.a1 to L.sub.a188, and L.sub.c is selected from any one of the group consisting of L.sub.c1 to L.sub.c231; when the second compound has a structure of Ir(L.sub.a)(L.sub.c).sub.2, L.sub.a is selected from any one of the group consisting of L.sub.a1 to L.sub.a188, and L.sub.c is selected from any one or any two of the group consisting of L.sub.c1 to L.sub.c231.

    [0273] According to an embodiment of the present disclosure, wherein, the second compound is selected from the group consisting of Compound C.sub.1 to Compound C.sub.173:

    ##STR00105## ##STR00106## ##STR00107## ##STR00108## ##STR00109## ##STR00110## ##STR00111## ##STR00112## ##STR00113## ##STR00114## ##STR00115## ##STR00116## ##STR00117## ##STR00118## ##STR00119## ##STR00120## ##STR00121## ##STR00122## ##STR00123## ##STR00124## ##STR00125## ##STR00126## ##STR00127## ##STR00128## ##STR00129## ##STR00130## ##STR00131## ##STR00132## ##STR00133## ##STR00134## ##STR00135## ##STR00136## ##STR00137## ##STR00138## ##STR00139## ##STR00140## ##STR00141## ##STR00142## ##STR00143##

    [0274] According to an embodiment of the present disclosure, wherein, the organic layer is a light-emitting layer, the first compound is a host material, and the second compound is a light-emitting material.

    [0275] According to an embodiment of the present disclosure, wherein, the device emits red light or white light.

    [0276] According to another embodiment of the present disclosure, further disclosed is a display assembly comprising an electroluminescent device, wherein the specific structure of the electroluminescent device is shown in any one of the preceding embodiments.

    [0277] According to another embodiment of the present disclosure, further disclosed is a compound combination comprising at least a first compound and a second compound;

    [0278] wherein the first compound has a structure of H-L-E, wherein the H has a structure represented by Formula A:

    ##STR00144##

    [0279] wherein in Formula A,

    [0280] Z.sub.1 to Z.sub.3 and Z.sub.6 to Z.sub.8 are, at each occurrence identically or differently, selected from CR.sub.z1 or N, Z.sub.4 and Z.sub.5 are, at each occurrence identically or differently, selected from CR.sub.z2, and two substituents R.sub.z2 in Z.sub.4 and Z.sub.5 are joined to form a ring;

    [0281] L is selected from a single bond, substituted or unsubstituted arylene having 6 to 30 carbon atoms, substituted or unsubstituted heteroarylene having 3 to 30 carbon atoms or a combination thereof;

    [0282] E is selected from substituted or unsubstituted aryl having 6 to 30 carbon atoms or substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms;

    [0283] R.sub.z1 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof;

    [0284] R.sub.z2 is, at each occurrence identically or differently, selected from the group consisting of: hydrogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0285] adjacent substituents R.sub.z1, R.sub.z2 can be optionally joined to form a ring;

    [0286] wherein the second compound is a metal complex, wherein the metal is selected from a metal with a relative atomic mass greater than 40, and the metal complex comprises a ligand L.sub.a which has a structure represented by Formula C:

    ##STR00145##

    [0287] wherein in Formula C, the ring A and the ring B are each independently selected from a five-membered unsaturated carbocyclic ring, an aromatic ring having 6 to 30 carbon atoms or a heteroaromatic ring having 3 to 30 carbon atoms;

    [0288] R.sub.i represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution; and R.sub.ii represents, at each occurrence identically or differently, mono-substitution, multiple substitutions or non-substitution;

    [0289] Y is selected from SiR.sub.yR.sub.y, GeR.sub.yR.sub.y, NR.sub.y, PR.sub.y, O, S or Se;

    [0290] when two R.sub.y are present, the two R.sub.y may be identical or different;

    [0291] X.sub.1 and X.sub.2 are, at each occurrence identically or differently, selected from CR.sub.x or N;

    [0292] R, R.sub.i, R.sub.ii, R.sub.x and R.sub.y are, at each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1 to 20 carbon atoms, a substituted or unsubstituted heterocyclic group having 3 to 20 ring atoms, substituted or unsubstituted arylalkyl having 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having 2 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having 3 to 20 carbon atoms, substituted or unsubstituted arylsilyl having 6 to 20 carbon atoms, substituted or unsubstituted amino having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, cyano, isocyano, hydroxyl, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group and combinations thereof, and

    [0293] adjacent substituents R.sub.i, R.sub.x, R.sub.y, R and R.sub.ii can be optionally joined to form a ring.

    [0294] Combination with Other Materials

    [0295] The materials described in the present disclosure for a particular layer in an organic light emitting device can be used in combination with various other materials present in the device. The combinations of these materials are described in more detail in U.S. Pat. App. No. 20160359122 at paragraphs 0132-0161, which is incorporated by reference herein in its entirety. The materials described or referred to the disclosure are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

    [0296] The materials described in the present disclosure for a particular layer in an organic light emitting device can be used in combination with various other materials present in the device. For example, a combination of the first compound and the second compound disclosed herein may be used in combination with a wide variety of emissive dopants, hosts, transport layers, blocking layers, injection layers, electrodes and other layers that may be present. The combination of these materials is described in detail in paragraphs 0080-0101 of U.S. Pat. App. No. 20150349273, which is incorporated by reference herein in its entirety. The materials described or referred to the disclosure are non-limiting examples of materials that may be useful in combination with the compounds disclosed herein, and one of skill in the art can readily consult the literature to identify other materials that may be useful in combination.

    [0297] The first compound and the second compound used in the present disclosure may be obtained with reference to preparation methods in the related art or may also be easily prepared with reference to patent applications of Publication Nos. or Application Nos. US20180337340A1, CN111868210A, CN202010285016.7, CN202010268985.1, CN202010285026.0, CN202010720191.4, CN202010825242.X, CN202011219604.7, CN202110348602.6 and so on, which is not repeated here. The method for preparing an electroluminescent device is not limited. The preparation methods in the following examples are merely examples and not to be construed as limitations. Those skilled in the art can make reasonable improvements on the preparation methods in the following examples based on the related art. Exemplarily, the proportions of various materials in a light-emitting layer are not particularly limited. Those skilled in the art can reasonably select the proportions within a certain range based on the related art. For example, taking the total weight of the materials in the light-emitting layer as reference, a host material may account for 80% to 99% and a light-emitting material may account for 1% to 20%; or the host material may account for 90% to 98% and the light-emitting material may account for 2% to 10%. Further, the host material may include one material or two materials, where a ratio of two host materials may be 100:0 to 1:99; or the ratio may be 80:20 to 20:80; or the ratio may be 60:40 to 40:60. In the embodiments of the device, the characteristics of the device were also tested using conventional equipment in the art (including, but not limited to, evaporator produced by ANGSTROM ENGINEERING, optical testing system produced by SUZHOU FATAR, life testing system produced by SUZHOU FATAR, and ellipsometer produced by BEIJING ELLITOP, etc.) by methods well known to the persons skilled in the art. As the persons skilled in the art are aware of the above-mentioned equipment use, test methods and other related contents, the inherent data of the sample can be obtained with certainty and without influence, so the above related contents are not further described in this patent.

    Device Example 1

    [0298] First, a glass substrate having an indium tin oxide (ITO) anode with a thickness of 120 nm was cleaned and then treated with oxygen plasma and UV ozone. After the treatment, the substrate was dried in a glovebox to remove moisture. Then, the substrate was mounted on a substrate holder and placed in a vacuum chamber. Organic layers specified below were sequentially deposited through vacuum thermal evaporation on the ITO anode at a rate of 0.2 to 2 Angstroms per second under a vacuum degree of about 10.sup.−8 torr. Compound HI was used as a hole injection layer (HIL) with a thickness of 100 Å. Compound HT was used as a hole transporting layer (HTL) with a thickness of 400 Å. Compound EB was used as an electron blocking layer (EBL) with a thickness of 50 Å. Then, Compound C.sub.8 as a dopant material and Compound 1-34 as a host material were co-deposited (at a weight ratio of 2:98) as an emissive layer (EML) with a thickness of 400 Å. Compound HB was used as a hole blocking layer (HBL) with a thickness of 50 Å. On the HBL, Compound ET and 8-hydroxyquinolinolato-lithium (Liq) were co-deposited as an electron transporting layer (ETL) with a thickness of 350 Å. Finally, Liq was deposited as an electron injection layer with a thickness of 1 nm, and A1 was deposited as a cathode with a thickness of 120 nm. The device was transferred back to the glovebox and encapsulated with a glass lid and a moisture getter to complete the device.

    Device Example 2

    [0299] The implementation mode in Device Example 2 was the same as that in Device Example 1, except that in the EML, Compound 1-34 was replaced with Compound 1-35 as the host material.

    Device Example 3

    [0300] The implementation mode in Device Example 3 was the same as that in Device Example 1, except that in the EML, Compound C.sub.8 was replaced with Compound C.sub.27 as the dopant material.

    Device Example 4

    [0301] The implementation mode in Device Example 4 was the same as that in Device Example 3, except that in the EML, Compound 1-34 was replaced with Compound 1-36 as the host material.

    Device Example 5

    [0302] The implementation mode in Device Example 5 was the same as that in Device Example 3, except that in the EML, Compound 1-34 was replaced with Compound 1-35 as the host material.

    Device Example 6

    [0303] The implementation mode in Device Example 6 was the same as that in Device Example 1, except that in the EML, Compound C.sub.8 was replaced with Compound C.sub.56 as the dopant material, and in the EML, the doping weight ratio of the dopant material to the host material was adjusted to 3:97.

    Device Example 7

    [0304] The implementation mode in Device Example 7 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.58 as the dopant material.

    Device Example 8

    [0305] The implementation mode in Device Example 8 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.87 as the dopant material.

    Device Example 9

    [0306] The implementation mode in Device Example 9 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.139 as the dopant material.

    Device Example 10

    [0307] The implementation mode in Device Example 10 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.140 as the dopant material.

    Device Example 11

    [0308] The implementation mode in Device Example 11 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.141 as the dopant material.

    Device Example 12

    [0309] The implementation mode in Device Example 12 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.144 as the dopant material.

    Device Example 13

    [0310] The implementation mode in Device Example 13 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.143 as the dopant material.

    Device Example 14

    [0311] The implementation mode in Device Example 14 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.146 as the dopant material.

    Device Example 15

    [0312] The implementation mode in Device Example 15 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.150 as the dopant material.

    Device Example 16

    [0313] The implementation mode in Device Example 16 was the same as that in Device Example 1, except that in the EML, Compound C.sub.8 was replaced with Compound C.sub.158 as the dopant material.

    Device Example 17

    [0314] The implementation mode in Device Example 17 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.163 as the dopant material.

    Device Example 18

    [0315] The implementation mode in Device Example 18 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.166 as the dopant material.

    Device Example 19

    [0316] The implementation mode in Device Example 19 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.167 as the dopant material.

    Device Example 20

    [0317] The implementation mode in Device Example 20 was the same as that in Device Example 6, except that in the EML, Compound C.sub.56 was replaced with Compound C.sub.173 as the dopant material.

    Device Comparative Example 1

    [0318] The implementation mode in Device Comparative Example 1 was the same as that in Device Example 1, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material, and Compound C.sub.8 was replaced with Compound RD-A as the dopant material.

    Device Comparative Example 2

    [0319] The implementation mode in Device Comparative Example 2 was the same as that in Device Comparative Example 1, except that in the EML, Compound H1 was replaced with Compound 1-34 as the host material.

    Device Comparative Example 3

    [0320] The implementation mode in Device Comparative Example 3 was the same as that in Device Comparative Example 1, except that in the EML, Compound H1 was replaced with Compound 1-36 as the host material.

    Device Comparative Example 4

    [0321] The implementation mode in Device Comparative Example 4 was the same as that in Device Comparative Example 1, except that in the EML, Compound H1 was replaced with Compound 1-35 as the host material.

    Device Comparative Example 5

    [0322] The implementation mode in Device Comparative Example 5 was the same as that in Device Example 1, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 6

    [0323] The implementation mode in Device Comparative Example 6 was the same as that in Device Example 3, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 7

    [0324] The implementation mode in Device Comparative Example 7 was the same as that in Device Example 6, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 8

    [0325] The implementation mode in Device Comparative Example 8 was the same as that in Device Example 7, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 9

    [0326] The implementation mode in Device Comparative Example 9 was the same as that in Device Example 8, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 10

    [0327] The implementation mode in Device Comparative Example 10 was the same as that in Device Example 9, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 11

    [0328] The implementation mode in Device Comparative Example 11 was the same as that in Device Example 10, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 12

    [0329] The implementation mode in Device Comparative Example 12 was the same as that in Device Example 11, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    Device Comparative Example 13

    [0330] The implementation mode in Device Comparative Example 13 was the same as that in Device Example 12, except that in the EML, Compound 1-34 was replaced with Compound H1 as the host material.

    [0331] The structures and thicknesses of layers of the devices are shown in the following table. A layer using more than one material is obtained by doping different compounds at their weight ratio as recorded.

    TABLE-US-00001 TABLE 1 Device structures in device examples and device comparative examples Device ID HIL HTL EBL EML HBL ETL Comparative Compound Compound Compound Compound Compound Compound Example 1 HI HT EB H1:Compound HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) RD-A (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 2 HI HT EB l-34:Compound HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) RD-A (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 3 HI HT EB l-36:Compound HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) RD-A (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 4 HI HT EB 1-35:Compound HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) RD-A (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 5 HI HT EB H1:Compound C.sub.8 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 6 HI HT EB H1:Compound C.sub.27 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 7 HI HT EB H1:Compound C.sub.56 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 8 HI HT EB H1:Compound C.sub.58 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 9 HI HT EB H1:Compound C.sub.87 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 10 HI HT EB H1:Compound C.sub.139 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 11 HI HT EB H1:Compound C.sub.140 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 12 HI HT EB H1:Compound C.sub.141 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Comparative Compound Compound Compound Compound Compound Compound Example 13 HI HT EB H1:Compound C.sub.144 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 1 Compound Compound Compound Compound Compound Compound HI HT EB 1-34:Compound C.sub.8 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 2 Compound Compound Compound Compound Compound Compound HI HT EB 1-35:Compound C.sub.8 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 3 Compound Compound Compound Compound Compound Compound HI HT EB 1-34:Compound C.sub.27 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 4 Compound Compound Compound Compound Compound Compound HI HT EB 1-36:Compound C.sub.27 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 5 Compound Compound Compound Compound Compound Compound HI HT EB 1-35:Compound C.sub.27 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 6 Compound Compound Compound Compound Compound Compound HI HT EB 1-34:Compound C.sub.56 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 7 Compound Compound Compound Compound Compound Compound HI HT EB 1-34:Compound C.sub.58 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 8 Compound Compound Compound Compound Compound Compound HI HT EB 1-34:Compound C.sub.87 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 9 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.139 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 10 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.140 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 11 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.141 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 12 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.144 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 13 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.143 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 14 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.146 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 15 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.150 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 16 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.158 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (98:2) (50 Å) (350 Å) (400 Å) Example 17 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.163 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 18 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.166 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 19 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.167 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å) Example 20 Compound Compound Compound Compound Compound Compound HI HT EB l-34:Compound C.sub.173 HB ET:Liq (40:60) (100 Å) (400 Å) (50 Å) (97:3) (50 Å) (350 Å) (400 Å)

    [0332] The structures of the materials used in the devices are shown as follows:

    ##STR00146## ##STR00147## ##STR00148## ##STR00149##

    [0333] Current-voltage-luminance (IVL) characteristics and lifetime characteristics of the devices were measured. Table 2 shows external quantum efficiency (EQE) data measured at a current density of 15 mA/cm.sup.2 and lifetime (LT97) data measured at initial brightness of 5000 cd/m.sup.2

    TABLE-US-00002 TABLE 2 Device data Device ID EQE (%) LT97 (h) Example 1 24.37 1234 Example 2 24.10 795 Example 3 25.50 1323 Example 4 25.21 689 Example 5 25.31 942 Example 6 25.08 1930 Example 7 24.57 2492 Example 8 25.94 1648 Example 9 23.53 821 Example 10 24.24 3184 Example 11 24.06 1071 Example 12 25.58 2332 Example 13 24.24 2016 Example 14 24.58 2504 Example 15 24.16 2107 Example 16 24.97 1169 Example 17 24.57 1803 Example 18 24.58 805 Example 19 24.43 774 Example 20 26.10 1603 Comparative 21.30 246 Example 1 Comparative 5.64 4 Example 2 Comparative 4.35 1 Example 3 Comparative 4.76 2 Example 4 Comparative 22.45 702 Example 5 Comparative 22.68 665 Example 6 Comparative 23.63 1242 Example 7 Comparative 23.06 1199 Example 8 Comparative 21.94 505 Example 9 Comparative 21.25 225 Example 10 Comparative 22.25 435 Example 11 Comparative 21.70 367 Example 12 Comparative 22.95 792 Example 13

    [0334] From the data comparison between Examples 1 and 2 and Comparative Example 5, it can be seen that a combination of the first compound and the second compound of the present disclosure can further improve the EQE of the device from 22.45% in Comparative Example 5, which has already reached a very high level, to 24.10% and 24.37%, respectively, which are significantly improved by 7.3% and 8.5%, respectively; more importantly, the compound combination of the present disclosure significantly extends the device lifetime from 702 hours in Comparative Example 5 to 1234 hours and 795 hours, respectively. It proves that the combination of the first compound and the second compound of the present disclosure has excellent performance that can significantly improve the EQE of the device and significantly extend the device lifetime. From the data comparison between Examples 3 to 5 and Comparative Example 6, it can be seen that the combination of the first compound and the second compound of the present disclosure can further improve the EQE of the device from 22.68% in Comparative Example 6, which has already reached a very high level, to 25.50%, 25.21% and 25.31%, respectively, which are significantly improved by 12.4%, 9.8% and 11.6%, respectively; more importantly, the compound combination of the present disclosure significantly extends the lifetime from 665 hours in Comparative Example 6 to 1323 hours, 689 hours and 942 hours in Examples 3 to 5, respectively. It proves that the combination of the first compound and the second compound of the present disclosure has the excellent performance that can significantly improve the EQE of the device and significantly extend the device lifetime. Similarly, from the data comparison between Example 6 and Comparative Example 7, the comparison between Example 7 and Comparative Example 8, the comparison between Example 8 and Comparative Example 9, the comparison between Example 9 and Comparative Example 10, the comparison between Example 10 and Comparative Example 11, the comparison between Example 11 and Comparative Example 12 and the comparison between Example 12 and Comparative Example 13, it again proves that the combination of the first compound and the second compound of the present disclosure can significantly improve the EQE of the device and significantly extend the device lifetime. Moreover, the comparison of these nine sets of data also proves that the combination of the first compound and the second compound of the present disclosure generally has excellent performance on improving device performance.

    [0335] These results show that the combination of the first compound and the second compound of the present disclosure can significantly improve the device performance and achieves a far better device effect than a commercially available host material, and these results fully prove the superiority of the combination of the first compound and the second compound of the present disclosure.

    [0336] Compared to Comparative Example 2, the device performance in Examples 1 and 3 has obvious advantages: compared to that in Comparative Example 2, the EQE in Examples 1 and 3 is improved by 332.1% and 352.1%, respectively, and compared to that in Comparative Example 2, the lifetimes are improved by several hundred times, reaching more than 1200 hours, which achieve very significant improvements. From the comparison between Examples 13 to 20 and Comparative Example 2, it can also be seen that the device performance in the examples has obvious advantages. Compared to that in Comparative Example 2, the device efficiency in Examples 13 to 20 is generally improved by several times, the device lifetimes in Examples 13 to 20 are generally improved by several hundred times, Example 20, in particular, has ultra-high device efficiency of 26.10% in the case of a long lifetime of 1603 h, indicating that the combination of the first compound and the second compound selected specifically in the present disclosure can significantly improve the device performance. Again, these results prove the superiority of the combination of the first compound and the second compound of the present disclosure.

    [0337] From the comparison between Comparative Example 1 and Comparative Examples 2 to 4, it can be found that when the same dopant Compound RD-A is used, the device performance in Comparative Examples 2 to 4 in which the first compound selected in the present disclosure is used as a host is significantly reduced compared to that in Comparative Example 1 in which the commercially available host material is used. According to the comparison between Examples 1 to 5 and Comparative Examples 5 and 6, it can be found that when the second compound selected in the present disclosure is used as the dopant material, the device performance in Examples 1 to 5 is significantly improved compared to that in Comparative Examples 5 and 6 in which the commercially available host material is used. From the above comparison, it can be found that although Compound RD-A and the second compound selected in the present disclosure are similar in structure, the combination of the second compound selected in the present disclosure and the first compound selected in the present disclosure unexpectedly and significantly improves the device performance. The completely different variation in device performance exhibited when such similar compound structures are combined with different compounds further shows the unpredictable superiority of the combination of the first compound and the second compound of the present disclosure.

    [0338] To conclude, the combination of the first compound and the second compound selected in the present disclosure can exhibit excellent device performance in the device, obtain higher EQE, and significantly extend the device lifetime. It proves that the combination of the first compound and the second compound selected in the present disclosure has an excellent application prospect.

    [0339] It is to be understood that various embodiments described herein are merely illustrative and not intended to limit the scope of the present disclosure. Therefore, it is apparent to the persons skilled in the art that the present disclosure as claimed may include variations of specific embodiments and preferred embodiments described herein. Many of the materials and structures described herein may be replaced with other materials and structures without departing from the spirit of the present disclosure. It is to be understood that various theories as to why the present disclosure works are not intended to be limiting.