COMPOUND FOR CAPPING LAYER AND ORGANIC LIGHT EMITTING DEVICE INCLUDING SAME

Abstract

A novel compound for a capping layer, and an organic light-emitting device containing the same are disclosed.

Claims

1. A compound for a capping layer, the compound being represented by Formula 1 below: ##STR00122## wherein Ar is a substituted or unsubstituted C6-C30 arylene group, L and L1 are each independently a direct bond, a substituted or unsubstituted C1-C50 alkylene group, a substituted or unsubstituted C2-C50 alkenylene group, a substituted or unsubstituted C1-C50 alkyleneoxy group, an ether group, a substituted or unsubstituted C1-C50 sulfide group, a thioether group, a substituted or unsubstituted C1-C50 carbonyl group, substituted or unsubstituted NR4C(X1)-, substituted or unsubstituted C(X2) NR5-, substituted or unsubstituted C(X3)-, substituted or unsubstituted NR6-, a substituted or unsubstituted C3-C50 cycloalkylene group, a substituted or unsubstituted C1-C50 heterocycloalkylene group, or a combination thereof, X, X1 to X3 are each independently O, S, Se, Te, NR7, or CR8R9, and R1 to R9 are each independently hydrogen, deuterium, halogen, a nitro group, a nitrile group, a hydroxy group, a thiol group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C50 alkyl group, a substituted or unsubstituted C2-C50 alkenyl group, a substituted or unsubstituted C1-C50 alkoxy group, a substituted or unsubstituted C1-C50 sulfide group, a substituted or unsubstituted silyl group, a substituted or unsubstituted C3-C50 cycloalkyl group, a substituted or unsubstituted C1 to C50 heterocycloalkyl group, a substituted or unsubstituted C3 to C50 aryl group, or a substituted or unsubstituted C2 to C50 heteroaryl group, and a plurality of adjacent R1 to R9 may or may not form a ring by bonding with each other.

2. The compound for a capping layer of claim 1, wherein Formula 1 is represented by Formula 2 below: ##STR00123## wherein in Formulas 2, same symbols as in Formula 1 above have same definitions as in Formula 1, and L2 is the same as the definition of L1 above.

3. The compound for a capping layer of claim 2, wherein two or more of R1 to R4 are each independently a substituted or unsubstituted C3-C50 cycloalkyl group, or a substituted or unsubstituted C1-C50 heterocycloalkyl group.

4. The compound for a capping layer of claim 2, wherein R1 and R3 are each independently a substituted or unsubstituted C3-C50 cycloalkyl group, or a substituted or unsubstituted C1-C50 heterocycloalkyl group.

5. The compound for a capping layer of claim 2, wherein one or more of R1 to R4 are each independently a substituted C3 to C50 cycloalkyl group or a substituted C1 to C50 heterocycloalkyl group.

6. The compound for a capping layer of claim 5, wherein substituents of R1 to R4 are each independently selected from the group consisting of hydroxyl groups, thiol groups, amino groups, nitrile groups, nitro groups, C1-C30 alkyl groups, C1-C30 halogenated alkyl groups, C1-C30 alkoxy groups, C1-C30 sulfide groups, silyl groups, halogen groups, C3-C30 cycloalkyl groups, C3-C30 cycloalkenyl groups, C1-C30 heterocycloalkyl groups, and combinations thereof.

7. The compound for a capping layer of claim 1, wherein the compound has an ortho-type bond in which N(-L1R2)-C(X)R1 and -L-R3 are bonded to two immediately adjacent carbons of Ar, or a meta-type bond in which N(-L1R2)-C(X)R1 and -L-R3 are bonded to two adjacent carbons on both sides of any carbon of Ar.

8. The compound for a capping layer of claim 1, wherein Ar is selected from Structural Formula Formulas A-1 to A-6: ##STR00124## wherein in Structural Formulas A-1 to A-6, Q is each independently a methyl group, an ethyl group, a t-butyl group, a cyclohexyl group, an adamantane group, a dihydroamine group, a dimethylamine group, a hydroxy group, a methoxy group, a mercaptan group, methylthio group, a fluoro group, a trifluoromethyl group, a nitrile group, a nitro group, a phenyl group, a pyridinyl group or a trimethylsilyl group, n is each independently an integer from 0 to 8, and indicates a bonding site.

9. The compound for a capping layer of claim 1, wherein in Formula 1, at least one of N(-L1R2)-C(X)R1 and -L-R3 is independently selected from Structural Formulas B-1 to B-43: ##STR00125## ##STR00126## ##STR00127## ##STR00128## ##STR00129## wherein in the structural Formulas, W1 is each independently a methyl group, an ethyl group, a t-butyl group, a cyclohexyl group, an adamantane group, a dihydroamine group, a dimethylamine group, a hydroxy group, a methoxy group, a mercaptan group, methylthio group, a fluoro group, a trifluoromethyl group, a nitrile group, a nitro group, or a trimethylsilyl group, n is each independently an integer from 0 to 10, and indicates a bonding site.

10. The compound for a capping layer of claim 9, wherein -L-R3 has each independently a structural formula in which CONH* in Structural Formulas B-1 to B-43 is replaced by Z* or *Z, in which Z is NHCS, NHC(?NH), CH2-NHCO, CH2-CONH, ONHCO, SNHCO, CONHCO, NHC(?NMe)-, NHC(?CHMe)-, NHCOO, NH, CONH, OCONH, SCONH, COCONH, CH2-, O, S, C0-, or .

11. The compound for a capping layer of claim 1, wherein in Formula 1, at least one of N(-L1R2)-C(X)R1 and -L-R3 is independently selected from Structural Formulas C-1 through C-14: ##STR00130## ##STR00131## ##STR00132##

12. The compound for a capping layer of claim 11, wherein -L-R3 has a structural formula in which CON* structure in Structural Formulas C-1 through C-14 is replaced by N*.

13. The compound for a capping layer of claim 1, wherein the compound is any one of the following compounds: ##STR00133## ##STR00134## ##STR00135## ##STR00136## ##STR00137## ##STR00138## ##STR00139## ##STR00140## ##STR00141## ##STR00142## ##STR00143## ##STR00144## ##STR00145## ##STR00146## ##STR00147## ##STR00148## ##STR00149## ##STR00150## ##STR00151## ##STR00152## ##STR00153## ##STR00154## ##STR00155## ##STR00156## ##STR00157## ##STR00158## ##STR00159## ##STR00160## ##STR00161## ##STR00162## ##STR00163## ##STR00164## ##STR00165## ##STR00166## ##STR00167## ##STR00168## ##STR00169## ##STR00170## ##STR00171## ##STR00172## ##STR00173## ##STR00174## ##STR00175## ##STR00176## ##STR00177## ##STR00178## ##STR00179## ##STR00180## ##STR00181## ##STR00182## ##STR00183## ##STR00184## ##STR00185## ##STR00186## ##STR00187##

14. The compound for a capping layer of claim 1, wherein the compound has a refractive index of 1.55 or less at a wavelength of 450 nm.

15. An organic light-emitting device comprising a capping layer comprising the compound for a capping layer of claim 1.

16. The organic light-emitting device of claim 15, wherein the organic light-emitting device comprises: a first electrode; a second electrode; and one or more organic layers interposed between the first electrode and the second electrode, wherein the capping layer is disposed on an outer surface of either one of the first electrode or the second electrode.

17. The organic light-emitting device of claim 15, wherein the capping layer has a thickness of 100 ? to 3000 ?.

18. The organic light-emitting device of claim 15, wherein the capping layer has a refractive index of 1.55 or less at a wavelength of 450 nm.

19. The organic light-emitting device of claim 16, wherein the capping layer comprises a first capping layer comprising the compound of claim 1 and a second capping layer having a refractive index higher than a refractive index of the first capping layer.

20. The organic light-emitting device of claim 19, wherein the first capping layer has the refractive index of 1.55 or less at a wavelength of 450 nm, the second capping layer has the refractive index of 2.10 or more at a wavelength of 450 nm, and a refractive index difference between the first capping layer and the second capping layer at a wavelength of 450 nm is in a range of 0.2 to 1.2.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0027] FIG. 1 is a schematic cross-sectional view illustrating the construction of an organic light-emitting device according to one embodiment of the present disclosure.

EXPLANATION OF DRAWING SYMBOLS

[0028] 100: substrate [0029] 200: Hole injection layer [0030] 300: Hole transport layer [0031] 400: light emitting layer [0032] 500: electron transport layer [0033] 600: Electron injection layer [0034] 1000: first electrode [0035] 2000: Second electrode [0036] 3000: capping layer

DETAILED DESCRIPTION

[0037] Prior to a description of the present disclosure, it should be noted that the terms used in the present specification are used only to describe specific examples and are not intended to limit the scope of the present disclosure which will be defined only by the appended claims.

[0038] Unless otherwise defined herein, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those who are ordinarily skilled in the art to which the present disclosure pertains.

[0039] Unless otherwise stated herein, it will be further understood that the terms comprise, comprises, and comprising, when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements and/or components but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and/or groups thereof.

[0040] Throughout the specification and claims of the disclosure, the term aryl refers to a functional group having a C5-50 aromatic hydrocarbon ring, and examples thereof include phenyl, benzyl, naphthyl, biphenyl, terphenyl, fluorene, phenanthrenyl, triphenylenyl, perylenyl, chrysenyl, fluoranthenyl, benzofluorenyl, benzotriphenylenyl, benzochrysenyl, anthracenyl, stilbenyl, or pyrenyl. The term heteroaryl refers to a C2-50 aromatic ring structure containing at least one heteroatom, and it includes a heterocyclic ring formed from pyrrolyl, pyrazinyl, pyridinyl, indolyl, isoindolyl, furyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, quinolyl group, isoquinolyl, quinoxalyl, carbazolyl, phenanthridinyl, acridinyl, phenanthrolinyl, thienyl, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, an indole ring, a quinoline ring, an acridine ring, a pyrrolidine ring, a dioxane ring, a piperidine ring, a morpholine ring, a piperazine ring, a carbazole ring, a furan ring, a thiophene ring, an oxazole ring, an oxadiazole ring, a benzofuran ring, a thiazole ring, a thiadiazole ring, a benzothiophene ring, a triazole ring, an imidazole ring, a benzoimidazole ring, a pyran ring, or a dibenzofuran ring.

[0041] In chemical formulas: Arx (where x is an integer) means a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group, unless otherwise defined; Lx (where x is an integer) means a directly bonded and substituted or unsubstituted C6-C50 arylene group or a substituted or unsubstituted C2-C50 heteroarylene group, unless otherwise defined; and Rx (where x is an integer), means a hydrogen, deuterium, halogen, a nitro group, a nitrile group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C1-C30 sulfide group, a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group, unless otherwise defined.

[0042] Throughout the present specification and claims, the term substituted or unsubstituted means that a portion is substituted or unsubstituted by at least one selected from the group consisting of deuterium, halogen, amino groups, cyano groups, nitrile groups, nitro groups, nitroso groups, sulfamoyl groups, isothiocyanate groups, thiocyanate groups, carboxyl groups, C1-C30 alkyl groups, C1-C30 alkylsulfinyl groups, C1-C30 alkylsulfonyl groups, C1-C30 alkylsulfanyl groups, C1-C12 fluoroalkyl groups, C2-C30 alkenyl groups, C1-C30 alkoxy groups, C1-C12 N-alkylamino groups, C2-C20 N,N-dialkylamino groups, substituted or unsubstituted C1-C30 sulfide groups, C1-C6 N-alkylsulfamoyl groups, C2-C12 N,N-dialkylsulfamoyl groups, C0-C30 silyl groups, C3-C20 cycloalkyl groups, C3-C20 heterocycloalkyl groups, C6-C50 aryl groups, C3-C50 heteroaryl groups, etc.

[0043] In addition, the same symbols throughout the present specification may have the same meaning unless otherwise specified.

[0044] All or some embodiments described herein may be selectively combined and configured so that the embodiments may be modified in various ways unless the context clearly indicates otherwise.

[0045] Hereinafter, embodiments of the present disclosure and the effects thereof will be described in detail below.

[0046] An organic light-emitting device according to an embodiment of the present disclosure may be an organic light-emitting device including a capping layer.

[0047] Specifically, the organic light-emitting device may include a first electrode, a second electrode, one or more organic layers disposed between the first electrode and the second electrode, and a capping layer disposed on an outer surface of either the first electrode or the second electrode and made of the compound of the present disclosure.

[0048] Specific examples of the compound of the present disclosure include compounds represented Formula 1 shown below.

##STR00002##

[0049] In Formula 1, [0050] Ar is a substituted or unsubstituted C6-C30 arylene group, [0051] L and L1 are each independently a direct bond, a substituted or unsubstituted C1-C50 alkylene group, a substituted or unsubstituted C2-C50 alkenylene group, a substituted or unsubstituted C1-C50 alkyleneoxy group, an ether group, a substituted or unsubstituted C1-C50 sulfide group, a thioether group, a substituted or unsubstituted C1-C50 carbonyl group, substituted or unsubstituted NR4C(X1)-, substituted or unsubstituted C(X2) NR5-, substituted or unsubstituted C(X3)-, substituted or unsubstituted NR6-, a substituted or unsubstituted C3-C50 cycloalkylene group, a substituted or unsubstituted C1-C50 heterocycloalkylene group, or a combination thereof, and specifically, it may be a combination of three or less of these.

[0052] Specifically, L may be substituted or unsubstituted NR4C(X1)-, substituted or unsubstituted C(X2)NR5-, or substituted or unsubstituted NR6-, and L1 may be a direct bond, a substituted or unsubstituted C1-C50 alkylene group, or a substituted or unsubstituted C1-C50 carbonyl group.

[0053] X, X1 to X3 are each independently O, S, Se, Te, NR7, or CR8R9, [0054] R1 to R9 are each independently hydrogen, deuterium, halogen, a nitro group, a nitrile group, a hydroxy group, a thiol group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C50 alkyl group, a substituted or unsubstituted C2-C50 alkenyl group, a substituted or unsubstituted C1-C50 alkoxy group, a substituted or unsubstituted C1-C50 sulfide group, a substituted or unsubstituted silyl group, a substituted or unsubstituted C3-C50 cycloalkyl group, a substituted or unsubstituted C1 to C50 heterocycloalkyl group, a substituted or unsubstituted C3 to C50 aryl group, or a substituted or unsubstituted C2 to C50 heteroaryl group, and a plurality of adjacent R1 to R9 may or may not form a ring by bonding with each other.

[0055] Specifically, one or more of R1 to R9 are each independently hydrogen, deuterium, a halogen group, a hydroxy group, a thiol group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C50 alkyl group, a substituted or unsubstituted C1-C50 alkoxy group, a substituted or unsubstituted C1-C50 sulfide group, a substituted or unsubstituted silyl group, a substituted or unsubstituted C3-C50 cycloalkyl group, or a substituted or unsubstituted C1-C50 heterocycloalkyl group.

[0056] In addition, in the specific examples of the capping layer compound of the present disclosure, the compound of Formula 1 refers a capping layer compound represented by Formula 2 shown below.

##STR00003##

[0057] In Formulas 2, the same symbols as in Formula 1 above have the same definitions as in Formula 1, [0058] L2 is the same as the definition of L1 above.

[0059] The capping layer compound of the present disclosure represented by Formula 2 has a structure in which the N of two amide-based substituents is directly bonded to an Ar linker, so it maintains a low refractive index and has excellent chemical and thermal stability.

[0060] In Formula 2, two or more of R1 to R4 may each independently be a substituted or unsubstituted C3-C50 cycloalkyl group, or a substituted or unsubstituted C1-C50 heterocycloalkyl group. This structure further improves thermal stability and can simultaneously lower the polarizability to form a low refractive index.

[0061] In addition, one or more of R1 to R4 may each independently be a substituted C3 to C50 cycloalkyl group or a substituted C1 to C50 heterocycloalkyl group. With the inclusion of a substituted structure, it can have high thermal stability.

[0062] Substituents of R1 to R4 are each independently selected from the group consisting of hydroxyl groups, thiol groups, amino groups, nitrile groups, nitro groups, C1-C30 alkyl groups, C1-C30 halogenated alkyl groups, C1-C30 alkoxy groups, C1-C30 sulfide groups, silyl groups, halogen groups, C3-C30 cycloalkyl groups, C3-C30 cycloalkenyl groups, C1-C30 heterocycloalkyl groups, and combinations thereof, but are not limited thereto. With the inclusion of these substituents, it is possible to maintain a low refractive index and high thermal stability.

[0063] Additionally, in Formulas 1 and 2, R1 and R3 may each independently be a substituted or unsubstituted C3-C50 cycloalkyl group, or a substituted or unsubstituted C1-C50 heterocycloalkyl group. This structure may form a lower refractive index by lowering the intramolecular polarizability and at the same time having a low extinction coefficient even in the short wavelength range.

[0064] In addition, when the amide-based linkers connected through the Ar core are bonded with each other in the ortho or meta position, they can have a lower refractive index and are more effective in improving the efficiency and lifespan of the organic light-emitting device.

[0065] That is, in Formula 1, it is an ortho-type bond in which N(-L1R2)-C(X)R1 and -L-R3 are bonded to two immediately adjacent carbons of Ar, or a meta-type bond in which N(-L1R2)-C(X)R1 and -L-R3 are bonded to two adjacent carbons on both sides of any carbon. This structure can have a lower refractive index, improving the efficiency and lifespan of the organic light-emitting device.

[0066] Furthermore, in Formula 1, Ar may be selected from Structural Formula Formulas A-1 to A-6 shown below.

##STR00004##

[0067] In Structural Formulas A-1 to A-6, Q is each independently a methyl group, an ethyl group, a t-butyl group, a cyclohexyl group, an adamantane group, a dihydroamine group, a dimethylamine group, a hydroxy group, a methoxy group, a mercaptan group, methylthio group, a fluoro group, a trifluoromethyl group, a nitrile group, a nitro group, a phenyl group, a pyridinyl group or a trimethylsilyl group, [0068] n is each independently an integer in a range of from 0 to 8, specifically an integer in a range of from 0 to 4, [0069] indicates a bonding site.

[0070] In addition, in Formula 1, at least one of N(-L1R2)-C(X)R1 and -L-R3 may each be independently selected from Structural Formulas B-1 to B-43 shown below.

##STR00005## ##STR00006## ##STR00007## ##STR00008## ##STR00009##

[0071] In the structural Formulas, W1 is each independently a methyl group, an ethyl group, a t-butyl group, a cyclohexyl group, an adamantane group, a dihydroamine group, a dimethylamine group, a hydroxy group, a methoxy group, a mercaptan group, methylthio group, a fluoro group, a trifluoromethyl group, a nitrile group, a nitro group, or a trimethylsilyl group, [0072] n is each independently an integer in a range of from 0 to 10, specifically an integer in a range of from 0 to 4, [0073] indicates a bonding site.

[0074] In addition, -L-R3 may each independently have a structural formula in which CONH* in Structural Formulas B-1 to B-43 is replaced by Z* or *Z, in which Z is NHCS, NHC(?NH), CH2-NHCO, CH2-CONH, ONHCO, SNHCO, CONHCO, NHC(?NMe)-, NHC(?CHMe)-, NHCOO, NH, CONH, OCONH, SCONH, COCONH, CH2-, O, S, C0-, or .

[0075] In addition, at least one of N(-L1R2)-C(X)R1 and -L-R3 may each be independently selected from Structural Formulas C-1 through C-14 shown below.

##STR00010## ##STR00011## ##STR00012##

[0076] In addition, -L-R3 may have a structural formula in which CON* structure in Structural Formulas C-1 through C-14 is replaced by N*.

[0077] In addition, the capping layer compound represented by Formula 1 may have a low refractive index, such as a refractive index of 1.55 or less at a wavelength of 450 nm, when the refractive index is measured for a thickness range of 20 nm to 100 nm. Specifically, the capping layer compound may have a refractive index of 1.50 or less at a wavelength of 450 nm and more specifically a low refractive index of 1.47 or less at a wavelength of 450 nm.

[0078] In addition, the compound of Formula 1 may be a capping layer compound represented by any one of the compounds shown below. The compounds shown below are presented only to help understanding of the present disclosure, and thus the scope of the present disclosure is not limited thereby.

##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027##

##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032## ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040## ##STR00041##

##STR00042## ##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047## ##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052## ##STR00053## ##STR00054## ##STR00055## ##STR00056## ##STR00057## ##STR00058## ##STR00059## ##STR00060## ##STR00061## ##STR00062## ##STR00063## ##STR00064##

[0079] One example of the compound of the present disclosure can be synthesized by schematic reaction formulas shown below.

##STR00065##

[0080] In another aspect of the present disclosure, there is provided an organic light-emitting device including a capping layer containing the capping layer compound described above.

[0081] Hereinafter, an organic light-emitting device according to one embodiment of the present disclosure will be described in detail.

[0082] According to one embodiment of the present disclosure, the organic light-emitting device includes a first electrode, a second electrode, one or more organic layers interposed between the first electrode and the second electrode, and a capping layer, in which the capping layer is disposed on the outer surface of either the first electrode or the second electrode.

[0083] Specifically, of the both surfaces of each of the first and second electrodes, a surface adjacent to the organic layer interposed between the first electrode and the second electrode is referred to as an inner surface, and a surface not adjacent to the organic material layer is referred to as an outer surface. That is, when the capping layer is disposed on the outer surface of the first electrode, the first electrode is interposed between the capping layer and the organic layer. When the capping layer is disposed on the outer surface of the second electrode, the second electrode is interposed between the capping layer and the organic layer.

[0084] According to one embodiment of the present disclosure, in the organic light-emitting device, one or more organic layers may be interposed between the first electrode and the second electrode or may be disposed on the outer surface of at least one of the first and second electrodes. That is, the capping layer may be formed on the outer surface of each of the first and second electrodes or may be formed on the outer surface of either one of the first and second electrodes. The capping layer may contain the capping layer compound according to the present disclosure. The capping layer may contain only one compound or two or more compounds, selected from the capping layer compounds of the present disclosure. The capping layer may contain one or more of the capping layer compounds and other known compounds.

[0085] The capping layer may have a thickness of 100 to 3000 ?.

[0086] On the other hand, the capping layer may have a composite capping layer structure in which a first capping layer having a relatively low refractive index and a second capping layer having a higher refractive index than the first capping layer are laminated. In this case, the compound for a capping layer, according to the present disclosure, may be included in the first capping layer. The stacking order of the first capping layer and the second capping layer is not limited. The first capping layer may be disposed on the outer side of the second capping layer. Alternatively, the second capping layer may be disposed on the outer side of the first capping layer. In a specific example, the second capping layer may be interposed between the first capping layer and the first or second electrode. Specifically, the second capping layer may be in contact with the first capping layer and the first electrode or in contact with the first capping layer and the second electrode.

[0087] In addition, the capping layer may be a multilayer structure in which a plurality of first capping layers and a plurality of second capping layers are stacked. The first capping layers and the second capping layers may be alternately stacked. That is, the stacking order is not limited as described above. The first capping layer may be disposed on the outer side of the second capping layer. Conversely, the second capping layer may be disposed on the outer side of the first capping layer.

[0088] In addition, the first capping layer may have a refractive index of 1.55 or less, specifically a refractive index of 1.50 or less, and more specifically a refractive index of 1.47 or less, at a wavelength of 450 nm. The second capping layer may have a refractive index of 2.10 or more, specifically a refractive index of 2.25 or more, and more specifically 2.30 or more, at a wavelength of 450 nm. The difference in refractive index between the first capping layer and the second capping layer at a wavelength of 450 nm may be in the range of 0.2 to 1.2 and more specifically 0.4 to 1.2. When the refractive index difference is less than 0.2 or greater than 1.2, the light extraction efficiency will be reduced.

[0089] The total thickness of the first capping layer may be in the range of from 50 ? to 2000 ?, and the total thickness of the second capping layer may be in the range of 50 ? to 2000 ?.

[0090] On the other hand, the capping layer may have a refractive index gradient. The refractive index gradient may have a descending profile in which the refractive index gradually decreases in an outward direction or an ascending profile in which the refractive index gradually increases in the outward direction. To this end, the refractive index gradient in the capping layer may be implemented by gradually varying the concentration of the capping layer compound according to the present disclosure during the formation of the capping layer.

[0091] On the other hand, the organic layers may include a hole transport layer, a light-emitting layer, and an electron transport layer that constitute a light-emitting unit but may not be limited thereto.

[0092] More specifically, the organic light-emitting device according to one embodiment of the present disclosure includes one or more organic layers between the first electrode (anode) and the second electrode (cathode), in which the organic layers are layers selected from a hole injection layer (HIL), a hole transport layer (HTL), and a light-emitting layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL). Optionally, a hole-blocking layer (HBL, not shown) or an electron transport auxiliary layer may be further disposed between the light-emitting layer (EML) and the electron transport layer (ETL), and an electron-blocking layer (EBL, not shown) or a light-emitting auxiliary layer may be disposed between the hole transport layer (HTL) and the light-emitting layer (EML).

[0093] FIG. 1 is a cross-sectional view schematically illustrating the construction of an organic light-emitting device according to one embodiment of the present disclosure. The organic light-emitting device according to one embodiment of the present disclosure may be manufactured to have a structure illustrated in FIG. 1.

[0094] Referring to FIG. 1, the organic light-emitting device includes a substrate 100, a first electrode 1000, a hole injection layer 200, a hole transport layer 300, a light-emitting layer 400, an electron transport layer 500, an electron injection layer 600, a second electrode 2000, and a capping layer 3000 that are stacked in this order. Although not shown in the illustration, the capping layer 3000 may be a laminate in which the first capping layer and the second capping layer are stacked on another, as described above. The capping layer 3000 may be a laminate that includes not only the first and second capping layers and a third capping layer having a different refractive index from each of the first and second capping layers. In addition, the capping layer may have a refractive index gradient. The refractive index gradient may have a descending profile in which the refractive index gradually decreases in an outward direction or an ascending profile in which the refractive index gradually increases in the outward direction.

[0095] Here, as the substrate 100, a substrate that is commonly used for organic light-emitting devices may be used. Specifically, a transparent glass substrate or a flexible plastic substrate excellent in mechanical strength, thermal stability, transparency, surface flatness, easy handling, and waterproofness may be used.

[0096] In the organic light-emitting device, the first electrode 1000 is used as a hole injection electrode for injecting holes.

[0097] The first electrode 1000 is made of a material having a low work function to enable hole injection. Specifically, the first electrode 1000 is made of a transparent material such as indium tin oxide (ITO), indium zinc oxide (IZO), or graphene.

[0098] The hole injection layer 200 may be formed by depositing a hole injection material on the first electrode 1000 by a method such as a vacuum deposition method, a spin coating method, a casting method, Langmuir-Blodgett (LB), or the like. In the case of using a vacuum deposition method to form the hole injection layer 200, the deposition conditions vary depending on the compound used as the material of the hole injection layer 200, the structure and thermal characteristics of the desired hole injection layer 200, and the like. The conditions are appropriately set to fall within a temperature range of 50? C. to 500? C., a vacuum degree range of 10-8 to 10-3 torr, a deposition rate range of 0.01 to 100 ?/sec, and a layer thickness range of 10 ? to 5 ?m. A charge generating layer may be optionally deposited on the surface of the hole injection layer 200 if necessary. A conventional material may be used as the material of the charge generation layer. For example, HATCN may be used.

[0099] The hole transport layer 300 may be formed by depositing a hole transport material on the hole injection layer 200 by a method such as a vacuum deposition method, a spin coating method, a casting method, or LB. In the case of forming the hole transport layer 300 by the vacuum deposition method, the deposition conditions vary depending on the compound used. However, the conditions may be selected from the same ranges described in connection with the hole injection layer 200. The hole transport layer 300 may be formed using a known compound. The hole transport layer 300 may be a single layer structure or a multilayer structure. Although not illustrated in FIG. 1, a light-emitting auxiliary layer may be additionally formed on the hole transport layer 300.

[0100] The light-emitting layer 400 may be formed by depositing a light-emitting material on the hole transport layer 300 or the light-emitting auxiliary layer by a method such as a vacuum deposition method, a spin coating method, a casting method, or LB. In the case of using a vacuum deposition method to form the light-emitting layer 400, the deposition conditions vary depending on the compound used. However, the conditions may be selected from the same ranges as in the deposition conditions of the hole injection layer 200. As the light-emitting material, a known compound may be used as a host or a dopant. The dopant is not limited to a specific substance. The light-emitting layer may be formed using a phosphorescent or fluorescent dopant. For example, BD142 (N6,N12-bis(3,4-dimethylphenyl)-N6,N12-dimethylchrysene-6,12-diamine) can be used as the fluorescent dopant, and the green phosphorescent dopant Ir(ppy)3 (tris(2-phenylpyridine) iridium), the blue phosphorescent dopant F2Irpic (iridium(III) bis[4,6-difluorophenyl-pyridinato-N,C2]picolinate), and the red phosphorescent dopant RD61 available from UDC Corporation can be vacuum-deposited (doped) together as the phosphorescent dopants. The doping concentration of the dopant is not particularly limited, but it is preferred that the doping concentration of the dopant may be in the range of from 0.01 to 15 parts by weight relative to 100 parts by weight of the host. When the content of the dopant is less than 0.01 wt %, since the amount of the dopant is insufficient, the coloration is not properly achieved. When the content of the dopant exceeds 15 wt %, the efficiency is sharply reduced due to the concentration quenching phenomenon.

[0101] Here, in the case where the phosphorescent dopant and the light-emitting material are used together, a hole-blocking material (HBL) may be deposited on the light-emitting layer 400 by a vacuum deposition method or a spin coating method to prevent triplet excitons or holes from diffusing into the electron transport layer 500. The material that can be used as the hole-blocking material is not particularly limited, and an arbitrary existing material may be selected and used. Examples of the hole blocking material include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, and hole blocking materials described in Japanese Patent Application Publication No. H11-329734 (A1). Representatively, Balq(bis(8-hydroxy-2-methylquinolinolato)-aluminum biphenoxide), and phenanthrolines-based compounds (for example, Bathocuproine (BCP) available from UDC) may be used. The light-emitting layer 400 used in the embodiment of the present disclosure may include one or more blue light-emitting layers.

[0102] The electron transport layer 500 is formed on the light-emitting layer 400 by a vacuum deposition method, a spin coating method, a casting method, or the like. The deposition conditions for the electron transport layer 500 vary depending on the compound used. However, the conditions may be selected from almost the same ranges as in the deposition conditions of the hole injection layer 200. For example, quinoline derivatives, in particular tris(8-quinolinolato)aluminum (Alq3), or 6,6-(3,4-dimethyl-1,1-dimethyl-1H-silol-2,5-diyl)di-2,2-bipyridine) (ET4), can be commonly used.

[0103] The electron injection layer 600 is formed by depositing an electron injection material on the electron transport 500 by a vacuum deposition method, a spin coating method, a casting method, or the like. As the material for the electron injection layer, LiF, NaCl, CsF, Li2O, BaO, and the like may be used.

[0104] The second electrode 2000 is used as an electron injection electrode and may be formed on the electron injection layer 600 by a method such as a vacuum deposition method or a sputtering method. Various metals may be used to form the second electrode 2000. Specific examples include, but are not limited to, lithium (Li), aluminum (Al), gold (Au), silver (Ag), magnesium (Mg), aluminum-lithium (AlLi), calcium (Ca), magnesium-indium (MgIn), and magnesium-silver (MgAg). A transmissive electrode made of ITO or IZO may be used to manufacture front-emission light-emitting devices.

[0105] The organic light-emitting device according to the present disclosure may be an organic light-emitting device including the first electrode 1000, the hole injection layer 200, the hole transport layer 300, the light-emitting layer 400, the electron transport layer 500, the electron injection layer 600, the second electrode 2000, and the capping layer 300. The organic light-emitting device may further include one or more intermediate layers if necessary.

[0106] On the other hand, the thickness of each organic layer formed according to the present disclosure can be adjusted as desired. Specifically, the thickness may fall within a range of from 1 to 1,000 nm and more specifically a range of from 1 to 150 nm.

[0107] The capping layer 3000 may be formed on the outer surface of the first electrode 1000, of the both surfaces of the first electrode 1000. That is, the capping layer 3000 may be formed on the surface that is not adjacent to the hole injection layer 200. In addition, of both surfaces (inner and outer surfaces) of the second electrode 2000, the capping layer 3000 may also be formed on the outer surface of the second electrode 2000. The outer surface is a surface that is not adjacent to the electron injection layer 600. The capping layer 3000 may be formed by a deposition process, and the capping layer 3000 may have a thickness in a range of 100 ? to 3,000 ? and more specifically a range of 300 ? to 2,000 ?. The thickness is adjusted to prevent a decrease in the transmittance of the capping layer 3000.

[0108] In addition, although not illustrated in FIG. 1, according to one embodiment of the present disclosure, organic layer having various functions may be additionally formed between the capping layer 3000 and the first electrode 1000 or between the capping layer 3000 and the second electrode 2000. Alternatively, organic layers having various functions may be additionally formed on the top surface (outer surface) of the capping layer 3000, and an additional functional layer may be provided in the middle of the capping layer 3000. However, the present disclosure is not limited to the structure described above.

[0109] Hereinafter, the present disclosure will be described in greater detail with reference to compound synthesis examples of and examples of organic light-emitting devices (OLEDs).

[0110] The OLED examples and compound synthesis examples described below are presented only for illustrative purposes and the scope of the present disclosure is not limited thereby.

Synthesis Example 1: Synthesis of Compound 19

[0111] ##STR00066##

[0112] In a round bottom flask, 5.0 g of 4-tert-butylcyclohexanecarbonyl chloride and 13.6 g of triethylamine were dissolved in 100 ml of 1,4-dioxane. Next, 1.33 g of benzene-1,4-diamine dissolved in 15 ml of 1,4-dioxane was slowly added to the flask, stirred for 5 hours at 60? C., and then stirred for 24 hours at room temperature. The reaction solution was added dropwise to 400 ml of a dilute hydrochloric acid solution, and the reaction ended. The precipitated solid was collected by filtering under reduced pressure, and then the solid was recrystallized to produce 4.6 g of Compound 19 (85% yield).

[0113] m/z: 440.3403 (100.0%), 441.3436 (30.3%), 442.3470 (4.4%)

Synthesis Example 2: Synthesis of Compound 20

[0114] ##STR00067##

[0115] Compound 20 was synthesized using benzene-1,3-diamine instead of benzene-1,4-diamine in the same manner as in Synthesis Example 1 (yield 81%).

[0116] m/z: 440.3403 (100.0%), 441.3436 (30.3%), 442.3470 (4.4%)

Synthesis Example 3: Synthesis of Compound 104

[0117] ##STR00068##

[0118] Compound 104 was synthesized using adamantane-1-carbonyl chloride and benzene-1,3-diamine instead of 4-tert-butylcyclohexanecarbonyl chloride and benzene-1,4-diamine in the same manner as Example 1 (yield 83%).

[0119] m/z: 432.2777 (100.0%), 433.2810 (30.3%), 434.2844 (4.4%)

Synthesis Example 4: Synthesis of Compound 105

[0120] ##STR00069##

[0121] Compound 105 was synthesized using adamantane-1-carbonyl chloride and benzene-1,2-diamine instead of 4-tert-butylcyclohexanecarbonyl chloride and benzene-1,4-diamine in the same manner as Example 1 (yield 83%).

[0122] m/z: 432.2777 (100.0%), 433.2810 (30.3%), 434.2844 (4.4%)

Synthesis Example 5: Synthesis of Compound 111

[0123] ##STR00070##

[0124] Compound 111 was synthesized using 3,5-Dimethyladamantane-1-carbonyl chloride and benzene-1,2-diamine instead of 4-tert-butylcyclohexanecarbonyl chloride and benzene-1,4-diamine in the same manner as Example 1 (yield 80%).

[0125] m/z: 488.3403 (100.0%), 489.3436 (34.6%), 490.3470 (5.8%)

Synthesis Examples 6 Through 25

[0126] Compounds were synthesized using Starting Material 1 and Starting Material 2 shown in Table 1 and Table 2 below instead of 4-tert-butylcyclohexanecarbonyl chloride and benzene-1,4-diamine in the same manner as in Example 1.

TABLE-US-00001 TABLE 1 Starting Starting Material 1 Material 2 m/z Synthesis Example 6 Compound 29 [00071] [00072] m/z: 414.30 (100.0%) Synthesis Example 7 Compound 35 [00073] [00074] m/z: 388.24 (100.0%) Synthesis Example 8 Compound 41 [00075] [00076] m/z: 420.19 (100.0%) Synthesis Example 9 Compound 44 [00077] [00078] m/z: 364.20 (100.0%) Synthesis Example 10 Compound 50 [00079] [00080] m/z: 464.19 (100.0%) Synthesis Example 11 Compound 62 [00081] [00082] m/z: 472.29 (100.0%) Synthesis Example 12 Compound 77 [00083] [00084] m/z: 356.25 (100.0%) Synthesis Example 13 Compound 86 [00085] [00086] m/z: 436.31 (100.0%) Synthesis Example 14 Compound 95 [00087] [00088] m/z: 436.31 (100.0%) Synthesis Example 15 Compound 101 [00089] [00090] m/z: 380.25 (100.0%) Synthesis Example 16 Compound 117 [00091] [00092] m/z: 488.34 (100.0%)

TABLE-US-00002 TABLE 2 Synthesis Example 17 Compound 118 [00093] [00094] m/z: 514.36 (100.0%) Synthesis Example 18 Compound 121 [00095] [00096] m/z: 462.29 (100.0%) Synthesis Example 19 Compound 148 [00097] [00098] m/z: 446.29 (100.0%) Synthesis Example 20 Compound 157 [00099] [00100] m/z: 458.29 (100.0%) Synthesis Example 21 Compound 161 [00101] [00102] m/z: 482.29 (100.0%) Synthesis Example 22 Compound 171 [00103] [00104] m/z: 532.31 (100.0%) Synthesis Example 23 Compound 185 [00105] [00106] m/z: 334.16 (100.0%) Synthesis Example 24 Compound 188 [00107] [00108] m/z: 366.12 (100.0%) Synthesis Example 25 Compound 191 [00109] [00110] m/z: 324.18 (100.0%)

Manufacturing Organic Light-Emitting Device

[0127] FIG. 1 illustrates the construction of a typical organic light-emitting device. In the present disclosure, an organic light-emitting device having the structure shown in FIG. 1 was manufactured as an example. Specifically, in the manufactured organic light-emitting device includes a, an anode (hole injection electrode 1000), a hole injection layer 200, a hole transport layer 300, a light-emitting layer 400, an electron transport layer 500, an electron injection layer 600, a cathode (electron injection electrode 2000), and a capping layer 3000 are stacked in this order from the bottom. The capping layer 3000 may be a multilayer structure in which the first capping layer and the second capping layer are combined.

[0128] When manufacturing the organic light-emitting device, as a substrate 10, a transparent glass substrate or a flexible plastic substrate is used.

[0129] In the organic light-emitting device, the hole injection electrode 1000 is used as the anode. For the hole injection electrode, a material having a low work function is used to enable hole injection. Specifically, the hole injection electrode is made of a transparent material such as indium tin oxide (ITO), indium zinc oxide (IZO), or graphene.

[0130] The materials used for the hole injection layer 200, hole transport layer 300, light-emitting layer 400, electron transport layer 500, electron injection layer 600, and high refractive index capping layer are summarized in Table 3 below.

[0131] In addition, the cathode 2000 for electron injection was formed on the electron injection layer 600. Various metals can be used to form the cathode. Specific examples of the metal include aluminum, gold, silver, magnesium, and magnesium-silver alloys.

TABLE-US-00003 TABLE 3 [00111] HT01 [00112] NDP9 [00113] BH01 [00114] BD01 [00115] ET01 [00116] Liq [00117] CPM01 (n 2.13 @ 450 nm)

Example 1

[0132] An indium tin oxide (ITO) substrate with a reflective layer containing silver (Ag) was cleaned with distilled water by ultrasonic cleaning. After the completion of the distilled water washing, the substrate was cleaned with a solvent such as isopropyl alcohol, acetone, or methanol by ultrasonic cleaning and then dried. As a hole-injection layer, HT01 doped with 3% by weight of NDP9 was formed to have a thickness of 100 ? on top of the ITO substrate. Next, HT01 with a thickness of 1000 ? was deposited thereon as a hole transport layer. BH01 (host layer) doped with 3% by weight of BD01 (dopant) was formed to have a thickness of 250 ? as a light-emitting layer. Next, an electron transport layer with a thickness of 300 ? was deposited using a mixture of ET01 and Liq (in a weight ratio of 1:1), and then LiF was deposited to form an electron injection layer with a thickness of 10 ?. MgAg was then deposited to a thickness of 15 nm to form a cathode. Next, a high refractive index capping layer with a thickness of 950 ? was formed on the cathode by depositing CPM01, and a low refractive index capping layer with a thickness of 400 ? was then formed by depositing the compound prepared in Synthesis Example 1. The resulting structure was encapsulated in a glove box to produce an organic light-emitting device.

Examples 2 to 25

[0133] Organic light-emitting devices were manufactured in the same manner as in Example 1 except that the compounds prepared in Synthesis Examples 2 to 25 were used, respectively, to form the respective low refractive index capping layers.

Comparative Examples 1 to 4

[0134] Organic light-emitting devices were manufactured in the same manner as in Example 1 except that Comparative Compounds 1 to 5 listed in Table 4 were respectively used to form the respective low refractive index capping layers.

TABLE-US-00004 TABLE 4 [00118] Comparative Compound 1 [00119] Comparative Compound 2 [00120] Comparative Compound 3 [00121] Comparative Compound 4

<Experimental Example 1> Performance Evaluation of Organic Light-Emitting Devices

[0135] Electrons and holes were injected by applying a voltage using a source measure unit (Kiethley 2400 manufactured by Keithley Instruments, Inc.) and the luminance was measured using a spectroradiometer (CS-2000 manufactured by Konica Minolta Inc.) when light is emitted. To evaluate the performance of each of the organic light-emitting devices of Examples 1 to 6, 16 to 18, 21 to 24, and Comparative Examples 1 to 4, the current density and luminance with respect to the applied voltage were measured under atmospheric pressure, and the results are shown in Table 5.

TABLE-US-00005 TABLE 5 Op. V mA/cm2 Cd/A CIEx CIEy LT97 Example 1 3.50 10 10.01 0.140 0.043 162 Example 2 3.50 10 10.99 0.140 0.042 165 Example 3 3.50 10 9.67 0.139 0.044 172 Example 4 3.50 10 11.06 0.139 0.042 178 Example 5 3.50 10 11.13 0.139 0.042 186 Example 14 3.50 10 9.61 0.139 0.042 168 Example 15 3.50 10 9.55 0.139 0.042 166 Example 16 3.50 10 9.68 0.139 0.042 176 Example 19 3.50 10 9.47 0.139 0.042 160 Example 21 3.50 10 9.33 0.140 0.043 157 Example 23 3.50 10 9.95 0.139 0.042 161 Example 24 3.50 10 9.93 0.139 0.042 160 Example 25 3.50 10 9.87 0.139 0.042 158 Comparative 3.53 10 6.36 0.134 0.054 77 Example 1 Comparative 3.51 10 8.15 0.135 0.047 145 Example 2 Comparative 3.52 10 7.35 0.137 0.050 117 Example 3 Comparative 3.51 10 8.33 0.137 0.047 50 Example 4

[0136] Comparing the examples of the present invention with the comparative examples, the present invention has a structure in which an amine is directly bonded to the arylene core and a substituent with a low polarizability, so the refractive index can be further lowered, and thus thin film formation and thermal stability are excellent, making it possible to provide organic light-emitting devices with high color purity, high efficiency, and long lifespan.

[0137] Specifically, comparing Example 1 and Example 2, the structure where the bonding position is a meta connection has a lower refractive index. In particular, comparing Example 3 and Example 4, the structure with an ortho-connected linker has a lower refractive index and is effective in improving efficiency. In addition, comparing Example 2 and Example 3, the structure with cyclohexylene as a substituent has a lower refractive index and is effective in improving efficiency, and the structure with adamantane has excellent thermal stability and is effective in improving lifespan. Lastly, comparing Example 4 and Example 5, it can be seen that the structure having an additional substituent further improves thermal stability and is effective in improving lifespan.

<Experimental Example 2> Evaluation of Refractive Index

[0138] With the use of each of the compounds of Synthesis Examples 1 to 5 and Comparative Compounds 1 to 4, deposition films with a thickness of 30 nm were formed on respective silicon substrates, and the refractive index at a wavelength of 450 nm was measured using an ellipsometer device (M-2000X available from J. A. Woollam Co., Inc.). The measurement results are summarized in Table 6.

TABLE-US-00006 TABLE 6 Com- Com- Com- Com- Com- Comparative Comparative Comparative Comparative pound pound pound pound pound Compound 1 Compound 2 Compound 3 Compound 4 19 20 104 105 111 n@450 nm 1.88 1.59 1.74 1.58 1.53 1.51 1.54 1.51 1.51

[0139] Referring to Table 6 above, it can be seen that the compounds according to the present disclosure exhibit a low refractive index of 1.55 or less at a wavelength of 450 nm. In addition, other compounds (not listed in Table 6) according to the present disclosure also exhibited a low refractive index of 1.55 or less at a wavelength of 450 nm.