THERMALLY-ACTIVATED SENSITIZED PHOSPHORESCENT ORGANIC ELECTROLUMINESCENT DEVICE

Abstract

A thermally activated, sensitized phosphorescence organic electroluminescence device includes a luminescent layer formed of a host material consisting of two materials, one being a hole transport material, and the other an electron transport material, at least one which is a thermally activated delayed fluorescence material. The host material is doped by a phosphorescent dye. The triplet state energy level of the CT excited state of the fluorescence material is higher than the triplet state energy level of the n-π excited state by 0 to 0.3 or the triplet state energy level of the CT excited state of the fluorescence material is higher than the triplet state energy level of the n-π excited state, wherein the difference is above 1.0 eV, and, a difference between the second triplet state energy level of its n-π excited state and the first singlet state energy level of its CT excited state is −0.1 to 0.1 eV.

Claims

1. A thermally activated and sensitized phosphorescence organic electroluminescence device, comprising: a luminescent layer, wherein: a host material of the luminescent layer consists of two materials, wherein one of the two materials is a hole transport material, the other is an electron transport material, and at least one of the two materials is a thermally activated delayed fluorescence material; and the host material is doped by a phosphorescent dye, and a proportion of the phosphorescent dye in the luminescent layer is <15 wt %, and the triplet state energy level of the CT excited state of the thermally activated delayed fluorescence material is higher than the triplet state energy level of the n-π excited state by 0 to 0.3; or, the triplet state energy level of the CT excited state of the thermally activated delayed fluorescence material is higher than the triplet state energy level of the n-π excited state, wherein the difference is above 1.0 eV, and, a difference between the second triplet state energy level of its n-π excited state and the first singlet state energy level of its CT excited state is-0.1 to 0.1 eV.

2. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 1, wherein, the proportion of the phosphorescent dye in the luminescent layer is 2 wt %-10 wt %.

3. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 1, wherein, the proportion of the phosphorescent dye in the luminescent layer is 2 wt %-3 wt %.

4. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 1, wherein, the thermally activated delayed fluorescence material is a material that has charge transfer transition, and the thermally activated delayed fluorescence material has both a donor group unit and an acceptor group unit therein, the donor group unit is a donor group or a group that is formed by linking two or more donor groups; the acceptor group unit is an acceptor group or a group that is formed by linking two or more acceptor groups; the donor group is selected from indolocarbazolyl; carbazolyl; bicarbazolyl; trianilino; phenoxazinyl; indolocarbazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; carbazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; bicarbazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; trianilino that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; or phenoxazinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; and the acceptor group is selected from naphthyl; anthryl; phenanthryl; pyrenyl; triazinyl; benzimidazolyl; cyano; pyridinyl; sulfonyl; phenanthroimidazolyl; naphthathiazolyl; benzothiazolyl; oxadiazolyl; naphthyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; anthryl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; phenanthryl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; pyrenyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; triazinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; benzimidazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; pyridinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; sulfonyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; phenanthroimidazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; naphthathiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; benzothiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; and oxadiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; wherein, one or more of the donor group unit and one or more of the acceptor group unit directly link to form the thermally activated delayed fluorescence material; or, one or more of the donor group unit and one or more of the acceptor group unit individually link to a linking group to form the thermally activated delayed fluorescence material, wherein the linking group is a group that has a steric hindrance.

5. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, one or two of the donor group units and one or two of the acceptor group units individually link to the linking group to form the thermally activated delayed fluorescence material, or one or two of the acceptor group units and one or two of the donor group units directly link to form the thermally activated delayed fluorescence material.

6. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, the linking group is selected from spirofluorenyl; phenyl; biphenyl; spirofluorenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl; phenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl; and biphenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl.

7. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, the donor group is selected from the following groups: ##STR00063## ##STR00064##

8. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, the acceptor group is selected from the following groups: ##STR00065##

9. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, the thermally activated delayed fluorescence material is a compound that has the following structures: ##STR00066## ##STR00067## ##STR00068## ##STR00069## ##STR00070## ##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075## ##STR00076## ##STR00077## ##STR00078## ##STR00079##

10. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 1, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

11. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 1, wherein, one of the two materials that the host material consists of is a thermally activated delayed fluorescence material, and the other is a regulating host material, wherein a triplet state energy level of the thermally activated delayed fluorescence material and a triplet state energy level of the regulating host material in the host material are equal.

12. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 2, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

13. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

14. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 5, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

15. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 6, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

16. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 9, wherein, both of the two materials that the host material consists of are thermally activated delayed fluorescence materials.

17. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 2, wherein, one of the two materials that the host material consists of is a thermally activated delayed fluorescence material, and the other is a regulating host material, wherein a triplet state energy level of the thermally activated delayed fluorescence material and a triplet state energy level of the regulating host material in the host material are equal.

18. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 4, wherein, one of the two materials that the host material consists of is a thermally activated delayed fluorescence material, and the other is a regulating host material, wherein a triplet state energy level of the thermally activated delayed fluorescence material and a triplet state energy level of the regulating host material in the host material are equal.

19. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 5, wherein, one of the two materials that the host material consists of is a thermally activated delayed fluorescence material, and the other is a regulating host material, wherein a triplet state energy level of the thermally activated delayed fluorescence material and a triplet state energy level of the regulating host material in the host material are equal.

20. The thermally activated and sensitized phosphorescence organic electroluminescence device according to claim 6, wherein, one of the two materials that the host material consists of is a thermally activated delayed fluorescence material, and the other is a regulating host material, wherein a triplet state energy level of the thermally activated delayed fluorescence material and a triplet state energy level of the regulating host material in the host material are equal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is the schematic diagram of the energy transfer of a conventional OLED luminescent layer phosphorescence system.

[0027] FIG. 2 is the schematic diagram of the structure of the organic electroluminescence device of the present invention.

[0028] FIG. 3 is the schematic diagram of the energy transfer of the OLED luminescent layer thermally activated and sensitized phosphorescence system of the present invention.

[0029] FIG. 4 is the schematic diagram of the energy transfer of the OLED luminescent layer of the present invention whose host materials are two TADF materials.

[0030] FIG. 5 is the schematic diagram of the energy transfer of the OLED luminescent layer of the present invention whose host materials are a TADF material and a regulating host material.

EMBODIMENTS OF THE PRESENT INVENTION

[0031] The present invention will be further illustrated below by referring to the drawings and the special examples, to enable a person skilled in the art to better understand and implement the present invention, but the examples are not taken as limiting the present invention.

[0032] As shown by FIG. 2, the organic electroluminescence device of the present invention comprises an anode 02, a hole transport layer 05, a luminescent layer 06, an electron transport layer 07 and a cathode 03, which are successively deposited on a substrate 01 and are laminated.

[0033] The thermally activated and sensitized organic electroluminescence device of the present invention comprises a luminescent layer, wherein the host material of the luminescent layer is a mixture of two materials, wherein one of the two materials is a hole transport material, the other is an electron transport material, and at least one of the two materials is a thermally activated delayed fluorescence material; and the host material is doped by a phosphorescent dye, and the doping concentration of the phosphorescent dye in the host material is <15 wt %, preferably 2 wt %-10 wt %, more preferably 2 wt %-3 wt %.

[0034] The triplet state energy level of the CT excited state of the thermally activated delayed fluorescence material is higher than the triplet state energy level of the n-π excited state by 0 to 0.3; or, the triplet state energy level of the CT excited state of the thermally activated delayed fluorescence material is higher than the triplet state energy level of the n-π excited state, wherein the difference is above 1.0 eV, and, a difference between the second triplet state energy level of its n-π excited state and the first singlet state energy level of its CT excited state is-0.1 to 0.1 eV.

[0035] As shown by FIG. 3, in the thermally activated and sensitized phosphorescence device of the present invention, one of the host materials of the luminescent layer is a hole transport material, the other is an electron transport material, and at least one of the two materials is a thermally activated delayed fluorescence material. In this manner, the energy of the triplet state excitons of the host material is transferred to the singlet state by reverse intersystem crossing, and then transferred to the triplet state of the phosphorescence material by long range Forster energy transfer, which improves the energy transfer relation between the host and guest luminophor, to reduce the doping proportion (<15%), save the cost, effectively suppress attenuation, and prolong the life. Additionally, the energy conversion and the luminescence are not in the same material, and thus the performance of the device is better.

[0036] In the present invention, preferably, the thermally activated delayed fluorescence material is a material whose triplet state energy level of the CT excited state is higher than the triplet state energy level of the n-π excited state with a difference between 0-0.3 eV; or, the thermally activated delayed fluorescence material is a material whose triplet state energy level of the CT excited state is higher than the triplet state energy level of the n-π excited state with a difference above 1.0 eV and whose difference between the second triplet state energy level of the n-π excited state and the first singlet state energy level of the CT excited state is −0.1 to 0.1 eV.

[0037] The thermally activated delayed fluorescence material of the present invention is a material whose difference between the triplet state of the CT excited state and the triplet state energy level of the n-π excited state is very small (0-0.3 eV), or a material whose above difference is very large (1.0 eV) but whose second triplet state of the n-π excited state is slightly smaller than or slightly higher than the first singlet state of the CT excited state (with a difference of (0-0.1 eV). All of the materials that the present invention selects have a donor group and an acceptor group that are separated spatially, thereby resulting in the spatial separation of the HOMO and LUMO energy levels and reducing overlap integral, and thus the difference between the energy level differences between the singlet states and the triplet states of the CT states of the materials is very small. Additionally, the energy level differences between the singlet states and the triplet states of the chosen phenanthroimidazolyl, naphthathiazolyl, benzothiazolyl or anthryl are above 1.0 eV, which can meet the requirements on the second material.

[0038] The thermally activated delayed fluorescence material in the present invention is a material that has charge transfer transition, and the thermally activated delayed fluorescence material has both a donor group unit and an acceptor group unit therein, wherein, the donor group unit is a donor group or a group that is formed by linking two or more donor groups; and the acceptor group unit is an acceptor group or a group that is formed by linking two or more acceptor groups. Specially, the structure of the host material may be donor-connection-acceptor, donor-acceptor-donor, and so on.

[0039] The donor group is selected from indolocarbazolyl; carbazolyl; bicarbazolyl; trianilino; phenoxazinyl; indolocarbazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; carbazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; dibenzofuranyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; trianilino that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; or phenoxazinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy or phenyl; and

[0040] the acceptor group is selected from naphthyl; anthryl; phenanthryl; pyrenyl; triazinyl; benzimidazolyl; cyano; pyridinyl; sulfonyl; phenanthroimidazolyl; naphthathiazolyl; benzothiazolyl; oxadiazolyl; naphthyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; anthryl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; phenanthryl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; pyrenyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; triazinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; benzimidazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; pyridinyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; sulfonyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; phenanthroimidazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; naphthathiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; benzothiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl; or oxadiazolyl that is substituted by one or more groups of C.sub.1-6 alkyl, methoxy, ethoxy, phenyl or pyridinyl;

[0041] wherein, one or more of the donor group units and one or more of the acceptor group units directly link to form the thermally activated delayed fluorescence material; or, one or more of the donor group units and one or more of the acceptor group units individually link to a linking group to form the thermally activated delayed fluorescence material, wherein the linking group is a group that has a steric hindrance.

[0042] The linking group is preferably selected from spirofluorenyl; phenyl; biphenyl; spirofluorenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl; phenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl; or biphenyl that is substituted by at least one of C.sub.1-6 alkyl or phenyl.

[0043] The donor group is preferably selected from the following structures:

##STR00016## ##STR00017##

[0044] The acceptor group is preferably selected from the following structures:

##STR00018##

[0045] Particularly, the thermally activated delayed fluorescence material is selected from the compounds having the following structures:

##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028##

3-3 (The ΔE.sub.ST of the CT state=0.03, and the energy level difference between the singlet state and the triplet state of the localized state is 1.1 eV, calculated by using Gaussian 03/TD-DFT)

##STR00029##

[0046] 3-4 (The ΔE.sub.ST of the CT state=0.05, and the energy level difference between the singlet state and the triplet state of the localized state is 1.2 eV, calculated by using Gaussian 03/TD-DFT)

##STR00030##

3-5 (The ΔE.sub.ST of the CT state=0.01, and the energy level difference between the singlet state and the triplet state of the localized state is 1.4 eV, calculated by using Gaussian 03/TD-DFT)

##STR00031## ##STR00032##

[0047] The syntheses of the relative compounds in the present application:

[0048] 1. The Synthesis of the Compound 1-7

##STR00033##

[0049] Synthesis 1-7a,

[0050] 3.34 g of carbazole, 3.22 g of 3,6-dibromocarbazole, 0.5 g of CuI, 0.5 g phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid. The solid is separated by using a chromatographic column to obtain the 1-7a, with a yield of 30%.

[0051] Mass spectrometry data: ESI-MS m/z: 498 [M.sup.+H].sup.+, elementary analysis: C.sub.36H.sub.23N.sub.3: C: 86.90, H: 4.66, N: 8.44.

[0052] Synthesis 1-7b,

[0053] 3.11 g of tribromobenzene, 2.48 g of p-methylbenzenethiol, 6 g of potassium carbonate, and 1 g of copper iodide are added into a 100 ml round bottom flask, and 50 ml of DMF is added. The mixture is heated at 100° C. under a nitrogen atmosphere for 24 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid. The solid is separated by using a chromatographic column to obtain the 1-7b, with a yield of 60%.

[0054] Mass spectrometry data: ESI-MS m/z: 401 [M.sup.+H].sup.+, elementary analysis: C.sub.20H.sub.17BrS, C: 59.85, H: 4.27.

[0055] Synthesis 1-7c,

[0056] In an ice water bath, 30 ml of the 1-7b is slowly dropped into a dichloromethane solution in 1 g of mCPBA, the mixture is maintained in the ice water bath till the addition ends, and subsequently the reaction is performed for 12 h. The solid is separated by using a chromatographic column to obtain the 1-7c, with a yield of 99%.

[0057] Mass spectrometry data: ESI-MS m/z: 465 [M.sup.+H].sup.+, elementary analysis: C.sub.20H.sub.17BrO.sub.4S.sub.2, C: 86.90, H: 4.66, N: 8.44.

[0058] Synthesis 1-7,

[0059] 4.97 g of 1-7a, 4.63 g of 1-7b, 0.5 g of CuI, 0.5 g of phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid. The solid is separated by using a chromatographic column to obtain the 1-7, with a yield of 60%.

[0060] Mass spectrometry data: ESI-MS m/z: 882 [M.sup.+H].sup.+, elementary analysis: C.sub.56H.sub.39N.sub.3O.sub.4S.sub.2, C, 76.25, H, 4.46, N, 4.76.

[0061] 2. The Synthesis of the Compound 1-4

[0062] The synthesis of the 1-4 can refer to that of the 1-7. Substance detection data: Mass spectrometry data: ESI-MS m/z: 717 [M.sup.+H].sup.+, elementary analysis C.sub.44H.sub.32N.sub.2O.sub.4S.sub.2, C: 73.72, H: 4.50, N: 3.91.

[0063] 3. The Synthesis of the Compound 1-8

##STR00034##

[0064] 4.52 g of 1-8a, 3 g of 1-8b and 0.05 g of tetrakis(triphenylphosphine)palladium, and 5.4 g of potassium carbonate are added into a round bottom flask, and then 30 ml of toluene, 20 ml of water and 5 ml of ethanol are added. The reaction is performed at 85° C. for 48 h. When the reaction ends, the mixture is extracted by using dichloromethane to obtain an organic layer, and then the organic layer is separated by using a chromatographic column to obtain the 1-8, with a yield of 65%.

[0065] Mass spectrometry data: ESI-MS m/z: 640 [M.sup.+H].sup.+, elementary analysis: C.sub.45H.sub.29N.sub.5, C: 84.48, H: 4.57, N: 10.95.

[0066] 4. The Synthesis of the Compound 2-1

##STR00035##

[0067] 2.43 g of 2-1a is added into an ultra-dry solution (30 ml) of 0.24 g of NaH, and is stirred at room temperature for 30 min. Then a DMF solution of 2.54 g of 2-1b is dropped into the above solution, heated to 100° C., and stirred for 1 hour. After being cooled, the mixture is poured into water, and the solid is filtered, and separated by using a chromatographic column, to obtain 2-1.

[0068] Mass spectrometry data: ESI-MS m/z: 701 [M.sup.+H].sup.+, elementary analysis: C.sub.48H.sub.32N.sub.2O.sub.2S, C: 82.26, H: 4.60, N: 4.0.

[0069] 5. The Synthesis of the Compound 2-2

[0070] The synthesis of the compound 2-2 can refer to that of 2-1, wherein the method is basically the same as that of the compound 2-1, and the difference is that the 2-1a is replaced by bicarbazole.

[0071] Mass spectrometry data: ESI-MS m/z: 879 [M.sup.+H].sup.+, elementary analysis: C.sub.60H.sub.38N.sub.4O.sub.2S, C: 81.98, H: 4.36, N: 6.37.

[0072] 6. The Synthesis of the Compound 2-7

##STR00036##

[0073] Synthesis 2-7a,

[0074] 2.25 g of 2,4-dichloro-6-phenyl triazine, 2 g of m-bromophenylboronic acid, 0.05 g of tetrakis(triphenylphosphine)palladium, and 5.4 g of potassium carbonate are added into a round bottom flask, and then 30 ml of toluene, 20 ml of water and 5 ml of ethanol are added. The reaction is performed at 85° C. for 48 h. When the reaction ends, the mixture is extracted by using dichloromethane to obtain an organic layer, and then the organic layer is separated by using a chromatographic column to obtain the 2-7a, with a yield of 58%.

[0075] Mass spectrometry data: ESI-MS m/z: 466 [M.sup.+H].sup.+, elementary analysis: C.sub.21H.sub.13Br.sub.2N.sub.3, C: 53.99, H: 2.80, N: 8.99.

[0076] Synthesis 2-7,

[0077] 4.65 g of 2-7a, 3.66 g of phenoxazine, 0.5 g of CuI, 0.5 g of phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid, The solid is separated by using a chromatographic column to obtain the 2-7, with a yield of 48%.

[0078] Mass spectrometry data: ESI-MS m/z: 672 [M.sup.+H].sup.+, elementary analysis: C.sub.45H.sub.29N.sub.5O.sub.2, C: 80.46, H: 4.35, N: 4.76.

[0079] 7. The Synthesis of the Compound 2-8

[0080] Synthesis 2-8a,

[0081] 2.25 g of 2,4-dichloro-6-phenyl triazine, 2 g of p-bromophenylboronic acid, 0.05 g of tetrakis(triphenylphosphine)palladium, and 5.4 g of potassium carbonate are added into a round bottom flask, and then 30 ml of toluene, 20 ml of water and 5 ml of ethanol are added. The reaction is performed at 85° C. for 48 h. When the reaction ends, the mixture is extracted by using dichloromethane to obtain an organic layer, and then the organic layer is separated by using a chromatographic column to obtain the 2-8a, with a yield of 55%.

[0082] Mass spectrometry data: ESI-MS m/z: 466 [M.sup.+H].sup.+, elementary analysis: C.sub.21H.sub.13Br.sub.2N.sub.3, C: 53.99, H: 2.80, N: 8.99.

[0083] Synthesis 2-8,

[0084] 4.65 g of 2-8a, 3.66 g of phenoxazine, 0.5 g of CuI, 0.5 g of phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid, The solid is separated by using a chromatographic column to obtain the 2-8, with a yield of 56%.

[0085] Mass spectrometry data: ESI-MS m/z: 640 [M.sup.+H].sup.+, elementary analysis: C.sub.45H.sub.29N.sub.5, C: 84.48, H: 4.57, N: 10.95.

[0086] 8. The Synthesis of the Compound 2-9

[0087] The synthesis of the 2-9 can refer to that of 2-7, wherein the difference is using a different donor group, by replacing phenoxazine with carbazole. 4.65 g of 2-8a, 3.0 g of carbazole, 0.5 g of CuI, 0.5 g of phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid, The solid is separated by using a chromatographic column to obtain the 2-9, with a yield of 50%.

[0088] Mass spectrometry data: ESI-MS m/z: 640 [M.sup.+H].sup.+, elementary analysis: C.sub.45H.sub.29N.sub.5, C: 84.48, H: 4.57, N: 10.95.

[0089] 9. The Synthesis of the Compound 2-11

##STR00037##

[0090] Synthesis 2-11,

[0091] 3.32 g of phenylindolocarbazole, 2.67 g 2-chloro-4,6-diphenyl triazine, 0.5 g of CuI, 0.5 g of phenanthroline and 5.2 g of potassium carbonate are added into a 100 ml round bottom flask, and 60 ml of DMF is added. The reaction is performed under a nitrogen atmosphere by heating to reflux for 48 hours. Subsequently the reaction liquid is poured into water, and is subject to vacuum filtration under reduced pressure to obtain a solid. The solid is separated by using a chromatographic column to obtain the 2-7, with a yield of 48%.

[0092] Mass spectrometry data: ESI-MS m/z: 564 [M.sup.+H].sup.+, elementary analysis: C.sub.39H.sub.25N.sub.5, C: 83.10, H: 4.47, N: 12.43.

[0093] 10. The Synthesis of the Compound 3-3

##STR00038##

[0094] Synthesis 3-3a,

[0095] 3 ml of pyridine is added into a mixed solution of o-phenylene diamine (0.6 g) and thionyl chloride (5 ml), stirred at 60° C. for 10 hours, extracted by using dichloromethane, and then washed by using a large amount of water to obtain a solid.

[0096] Mass spectrometry data: ESI-MS m/z: 205.

[0097] Synthesis 3-3b,

[0098] 2.25 g of 3-3a, 2 g of phenylboronic acid, 0.05 g of tetrakis(triphenylphosphine)palladium, and 5.4 g of potassium carbonate are added into a round bottom flask, and then 30 ml of toluene, 20 ml of water and 5 ml of ethanol are added. The reaction is performed at 85° C. for 48 h. When the reaction ends, the mixture is extracted by using dichloromethane to obtain an organic layer, and then the organic layer is separated by using a chromatographic column to obtain the 3-3a, with a yield of 58%.

[0099] Mass spectrometry data: ESI-MS m/z: 246 [M.sup.+H].sup.+.

[0100] Synthesis 3-3,

[0101] 2.46 g of 3-3b, 2.39 g of 4-boric acid triphenylamine, 0.05 g of tetrakis(triphenylphosphine)palladium, and 5.4 g of potassium carbonate are added into a round bottom flask, and then 30 ml of toluene, 20 ml of water and 5 ml of ethanol are added. The reaction is performed at 85° C. for 48 h, When the reaction ends, the mixture is extracted by using dichloromethane to obtain an organic layer, and then the organic layer is separated by using a chromatographic column to obtain the 3-3, with a yield of 58%.

[0102] Mass spectrometry data: ESI-MS m/z: 456 [M.sup.+H].sup.+, elementary analysis: C.sub.30H.sub.21N.sub.3S, C: 79.09, H: 4.65, N: 9.22.

[0103] 11. The Synthesis of the Compound 3-4

[0104] The synthesis of the compound 3-4 can refer to the compound 3-3, wherein the steps are basically the same, and the difference is that the acceptor group is benzothiazole substituted by thiophene.

[0105] Mass spectrometry data: ESI-MS m/z: 462 [M.sup.+H].sup.+, elementary analysis: C.sub.28H.sub.19N.sub.3S.sub.2: C: 72.86, H: 4.15, N: 9.10.

[0106] 12. The Synthesis of the Compound 3-5

[0107] The synthesis of the compound 3-5 can refer to the compound 3-3, wherein the steps are basically the same, and the difference is that the acceptor group is naphthathiazole substituted by thiophene.

[0108] Mass spectrometry data: ESI-MS m/z: 512 [M.sup.+H].sup.+, elementary analysis: C.sub.32H.sub.21N.sub.3S.sub.2: C: 75.12, H: 4.15, N: 8.21.

[0109] The two materials that the host material consists of of the present invention may both be a thermally activated delayed fluorescence material, and the energy transfer process is as shown by FIG. 4: the first TADF host and the second TADF host individually transfer the triplet state energy to the singlet state by reverse intersystem crossing, and then transfer all of the energy to the triplet state of the phosphorescent dye by Forster, thereby reducing the distance between the host and the guest, to utilize the energy of the host with a high efficiency and reduce the consumption of the phosphorescence materials, and effectively solving the problem of roll-off, to improve the stability of the device.

[0110] Alternatively, one of the two materials is a thermally activated delayed fluorescence material (the TADF host), and the other is a regulating host material (regulating host). One of them is an electron transport material, and the other is a hole transport material. The energy transfer principle is as shown by FIG. 5: the common triplet state energy of the TADF host and the regulating host is transferred to the singlet state by reverse intersystem crossing, and then transfer all of the energy to the triplet state of the phosphorescent dye by Forster, thereby reducing the distance between the host and the guest, to utilize the energy of the host with a high efficiency and reduce the consumption of the phosphorescence materials, and effectively solving the problem of roll-off, to improve the stability of the device.

[0111] The embodiments of the organic luminescence display device of the present invention: The anode may employ an inorganic material or an organic conductive polymer. The inorganic material may generally employ metal oxides such as indium tin oxide (ITO), zinc oxide (ZnO), and indium zinc oxide (IZO) or metals of high work functions such as gold, copper and silver, preferably ITO. The organic conductive polymer is preferably one of polythiophene/polyvinyl sodium benzenesulfonate (hereafter referred to as simply PEDOT/PSS) and polyaniline (hereafter referred to as simply PANI).

[0112] The cathode generally employs metals of low work function such as lithium, magnesium, calcium, strontium, aluminum and indium or their alloys with copper, gold or silver, or an electrode layer that is formed by the alternating of a metal and a metal fluoride. In the present invention the cathode is preferably laminated LiF layer and Al layer (the LiF layer is on the outer side).

[0113] The material of the hole transport layer may be selected from lower molecular weight materials of the arylamine type and the branched polymer type, preferably NPB.

[0114] The material of the electron transport layer may employ an organic metal complex (such as Alq.sub.3, Gaq.sub.3, BAlq or Ga (Saph-q)) or other materials that are commonly used for electron transport layer, such as aromatic condensed ring type (such as pentacene and perylene) or o-phenanthroline type (such as Bphen and BCP) compounds.

[0115] The organic electroluminescence device of the present invention may also be provided with a hole injection layer 04 (which may be omitted) between the anode and the hole transport layer. The material of the hole injection layer may employ, for example, 4,4′,4″-tris(3-methylphenylaniline)triphenylamine) doped F4TCNQ or copper phthalocyanine (CuPc), or may be a metal oxide, such as molybdenum oxide and rhenium oxide.

[0116] The thicknesses of the layers may employ the conventional thicknesses of the layers in the art.

[0117] The present invention further provides the preparation method of the organic electroluminescence device, which comprises successively depositing on the substrate 01 the anode 02, the hole transport layer 05, the luminescent layer 06, the electron transport layer 07 and the cathode 03, which are laminated, and packaging.

[0118] The substrate may be glass or a flexible base sheet. The flexible base sheet may employ a polyester type or polyimide type compound material or a thin sheet metal. The laminating and the packaging may employ any suitable method that is known by a person skilled in the art.

[0119] For convenience, the abbreviations and full names of some organic materials that are involved in the description are listed as follows:

TABLE-US-00001 Abbreviation Full name Structural formula Alq.sub.3 tris(8- hydroxylquinoline)aluminum [00039] BAlq di(2-methyl-8-quinolinyl)-4- phenylphenolaluminum (III) [00040] BCP 2,9-dimethyl-4,7-diphenyl- 1,10-o-phenanthroline [00041] Bphen 4,7-diphenyl-1,10-o- phenanthroline [00042] C545T 10-(2-benzothiazole)- 1,1,7,7,-tetramethyl-2,3,6,7- tetrahydro-1H,5H,11H- benzo[1]pyran[6,7,8- ij]quinolizine [00043] CBP 4,4′-N,N′-dicarbazole- biphenyl [00044] CPF 9,9-di(4-dicarbazole- phenyl)fluorine [00045] m-MTDATA 4,4′,4″-tris(3- methylphenylaniline) triphenylamine [00046] NPB N,N′-di-(1-naphthyl)-N,N′- diphenyl-1,1′-biphenyl-4,4′- diamine [00047] PBD 2-(4-tertbutylphenyl)-5-(4- biphenyl)-1,3,4-oxadiazol [00048] Pentacene pentacene [00049] TPD N,N′-diphenyl-N,N′-bis(m- methylphenyl)-1,1′-biphenyl- 4,4′-diamine [00050] perylene perylene [00051] DCJTB 4-4-dicyanomethylene-2- tertbutyl-6-(1,1,7,7- tetramethyl-julolidine-9- ethenyl)-4H-pyran [00052] DCM 4-dicyanomethylene-2- methyl-6-(p- dimethylaminostyrenyl)-4H- pyran [00053] Rubrene 5,6,11,12- tetraphenyltetracene [00054] DCM-1 4-(dimercaptomethylene)-2- methyl-6-(p- dimethylaminostyrenyl)-4H- pyrane [00055] DMQA N,N′-dimethylquinacridone [00056] F4TCNQ 2,3,5,6-tetrafluoro-7,7′,8,8′- tetracyanodimethyl-p- benzoquinone [00057] niBr N-2,6-dibromophenyl-1,8- naphthalimide [00058] TCTA 4,4′,4″-tris(carbazol-9- yl)trianiline [00059] mCP 1,3-dicarbazol-9-ylbenzene [00060] Ir(ppy).sub.3 tris(2-phenylpyridine) iridium(III) [00061] Ir(piq)3 tris(1-phenyl-isoquinoline) iridium(III) [00062]

[0120] The present invention is further illustrated below by the Examples.

Example 1

[0121] In this Example luminescence devices that have different doping concentrations of thermally activated delayed fluorescence materials are prepared, and those devices have the structure as shown by FIG. 3. The host materials of the luminescent layers (thermally activated delayed fluorescence materials Host1 (1-9), thermally activated delayed fluorescence materials Host2 (2-4), the phosphorescent dye doping the host materials (Ir(ppy).sub.3). The thermally activated delayed fluorescence materials Host2 (2-4) are electron transport materials, and the thermally activated delayed fluorescence materials Host1 (1-9) are hole transport materials):

[0122] The structure of the device of this Example is as follows: ITO (150 nm)/NPB (40 nm)/host material: (2%, 3%, 10%, 14%) phosphorescent dye (30 nm)/Alq.sub.3 (20 nm)/LiF (0.5 nm)/Al (150 nm)

[0123] In that, the percentages in the parentheses preceding the phosphorescent dye indicate different doping concentrations, and in this Example and below, the doping concentrations are all in wt %.

[0124] The particular preparation method of the organic electroluminescence device is as follows:

[0125] Firstly, washing a glass substrate by using a detergent and deionized water, drying it in an infrared lamp, and sputtering a layer of anode material on the glass, with the film thickness of 150 nm;

[0126] then, placing the glass substrate having an anode into a vacuum cavity, vacuumizing to 1×10.sub.−4 Pa, and continually coating by vaporization NPB on the anode layer film as the hole transport layer, with the film forming speed of 0.1 nm/s and the vaporization coating film thickness of 40 nm;

[0127] coating by vaporization the luminescent layer on the hole transport layer, by the approach of double source co-vaporization, by adjusting the film forming speed by using a film thickness monitor according to the mass percentage between the host material and the phosphorescent dye, with the vaporization coating film thickness of 30 nm;

[0128] continually coating by vaporization a layer of Alq.sub.3 material on the luminescent layer as the electron transport layer, with the vaporization coating speed of 0.1 nm/s and the total vaporization coating film thickness of 20 nm; and

[0129] finally coating by vaporization successively a LiF layer and an Al layer on the luminescent layer as the cathode layer of the device, wherein the vaporization coating speed of the LiF layer is 0.01-0.02 nm/s and the thickness is 0.5 nm, and the vaporization coating speed of the Al layer is 1.0 nm/s and the thickness is 150 nm.

Comparative Example 1

[0130] An organic electroluminescence device is prepared by using the method the same as that of Example 1, and the structure of the device is as follows:

[0131] ITO (150 nm)/NPB (40 nm)/host material: (15%) phosphorescent dye (30 nm)/Alq.sub.3 (20 nm)/LiF (0.5 nm)/Al (150 nm)

[0132] The host material of the luminescent layer is CBP:BAlq, and the phosphorescent dye is the same as that of Example 1.

Comparative Example 2

[0133] An organic electroluminescence device is prepared by using the method the same as that of Example 1, and the structure of the device is as follows:

[0134] ITO (150 nm)/NPB (40 nm)/host material: (15%, 20%) phosphorescent dye (30 nm)/Alq.sub.3 (20 nm)/LiF (0.5 nm)/Al (150 nm)

[0135] The host materials of the luminescent layers (thermally activated delayed fluorescence materials Host1 (1-9), thermally activated delayed fluorescence materials Host2 (2-4)), and the phosphorescent dye is the same as that of Example 1.

[0136] The performances of the organic electroluminescence devices of Example 1 and Comparative Example 1 are presented in Table 1, and the percentages of the luminescent layer compositions in the table indicate the mass percentages of the components in the luminescent layers:

TABLE-US-00002 TABLE 1 External Luminescence Quantum Life Luminescent Layer Efficiency Luminance Efficiency T90 Device Composition (cd/A) (cd/m.sup.2) (%) (hrs) Example 1 host material (thermally 44.5 5000 12.5 390 activated delayed fluorescence material Host 1 (1-9) (39 wt %), thermally activated delayed fluorescence material Host 2 (2-4) (59 wt %):phosphorescent dye (2 wt %) host material (thermally 46.0 5000 13.3 421 activated delayed fluorescence material Host 1 (1-9) (38 wt %), thermally activated delayed fluorescence material Host 2 (2-4) (59 wt %):phosphorescent dye (3 wt %) host material (thermally 38.4 5000 11.4 378 activated delayed fluorescence material Host 1 (1-9) (36%), thermally activated delayed fluorescence material Host 2 (2-4) (54%):phosphorescent dye (10%) host material (thermally 35.1 5000 10.1 370 activated delayed fluorescence material Host 1 (1-9) (34%), thermally activated delayed fluorescence material Host 2 (2-4) (52%)):phosphorescent dye (14%) Comparative host material (CBP 28.0 5000 8.0 289 Example 1 (34%):BAlq (51%)):phosphorescent dye (15%) Comparative host material (thermally 32.7 5000 9.7 345 Example 2 activated delayed fluorescence material Host 1 (1-9) (34%), thermally activated delayed fluorescence material Host 2 (2-4) (51%):phosphorescent dye (15%) host material (thermally 29 5000 6.4 296 activated delayed fluorescence material Host 1 (1-9) (32%), thermally activated delayed fluorescence material Host 2 (2-4) (48%):phosphorescent dye (20%)

[0137] It can be seen from Table 1 that, when the host material employs the mixture of an electron transport material and a hole transport material, and they both employ a TADF material, the luminescence efficiencies of the double thermally activated delayed fluorescence host materials are obviously increased compared with the efficiency of the single host material, and the lives are also obviously increased compared with the lives of the traditional double host devices.

[0138] In addition, when the doping concentrations of the phosphorescent dyes are less than 15%, their luminescence efficiencies are all higher than the efficiencies when the doping concentrations are >15%, the lives are also increased, and the big amount of the consumption of the expensive phosphorescent dye is eliminated.

Example 2

[0139] In this Example luminescence devices that have different doping concentrations of thermally activated delayed fluorescence materials are prepared, and those devices have the structure as shown by FIG. 3. The host materials of the luminescent layers (thermally activated delayed fluorescence materials Host 3 (1-10), regulating host material (CBP), the phosphorescent dye doping the host materials Ir(piq).sub.3. The thermally activated delayed fluorescence materials Host 3 (1-10) are electron transport materials, and the regulating host material CBP is a hole transport material, wherein their triplet state energy levels are the same): the structure of the device of this Example is as follows:

[0140] ITO (150 nm)/NPB (40 nm)/host material: (2%, 3%, 10%, 14%) phosphorescent dye (30 nm)/Alq.sub.3 (20 nm)/LiF (0.5 nm)/Al (150 nm)

[0141] In that, the percentages in the parentheses preceding the phosphorescent dye indicate different doping concentrations, and in this Example and below, the doping concentrations are all in wt %.

Comparative Example 3

[0142] An organic electroluminescence device is prepared by using the method the same as that of Example 1, and the structure of the device is as follows:

[0143] ITO (150 nm)/NPB (40 nm)/host material: (15%, 20%) phosphorescent dye (30 nm)/Alq.sub.3 (20 nm)/LiF (0.5 nm)/Al (150 nm)

[0144] The host materials of the luminescent layers (thermally activated delayed fluorescence materials Host 3 (1-10)), regulating host material CBP, and the phosphorescent dye is the same as that of Example 2.

[0145] The performances of the organic electroluminescence devices of Example 2 and Comparative Example 3 are as shown by Table 2:

TABLE-US-00003 TABLE 2 External Luminescence Quantum Life Luminescent Layer Efficiency Luminance Efficiency T90 Device Composition (cd/A) (cd/m.sup.2) (%) (hrs) Example 2 host material (thermally 48.6 5000 18.0 457 activated delayed fluorescence material Host 3 (1-10) (59%), regulating host material CBP (39%):phosphorescent dye (2%) host material (thermally 53.5 5000 19.3 490 activated delayed fluorescence material Host 3 (1-10) (59%), regulating host material CBP (38%):phosphorescent dye (3%) host material (thermally 45.1 5000 17.4 423 activated delayed fluorescence material Host 3 (1-10) (54%), regulating host material CBP (36%):phosphorescent dye (10%) host material (thermally 42.5 5000 16.9 410 activated delayed fluorescence material Host 3 (1-10) (52%), regulating host material CBP (34%):phosphorescent dye (14%) Comparative host material (thermally 41.7 5000 16.8 407 Example 3 activated delayed fluorescence material Host 3 (1-10) (51%), regulating host material CBP (34%):phosphorescent dye (15%) host material (thermally 39.2 5000 13.5 389 activated delayed fluorescence material Host 3 (1-10) (48%), regulating host material CBP (32%):phosphorescent dye (20%)

[0146] It can be seen from Table 2 that, when the doping concentrations of the phosphorescent dyes are less than 15%, their luminescence efficiencies are all higher than the efficiencies when the doping concentrations are >15%, the lives are also increased, and the big amount of the consumption of the expensive phosphorescent dye is eliminated.

Example 3

[0147] In order to test the influence of the host materials of the present invention on the performance of the organic electroluminescence device, in this Example an organic electroluminescence device is prepared by using the method the same as that of Example 1, and the structure of the luminescence device is as follows:

[0148] ITO (150 nm)/NPB (40 nm)/host material (the mass ratio of the two host materials is 1:1): 3% phosphorescent dye (Ir(ppy).sub.3) (30 nm)/Bphen (20 nm)/LiF (0.5 nm)/Al (150 nm).

[0149] The performance of the organic electroluminescence device is presented in Table 3:

TABLE-US-00004 TABLE 3 External Luminescence Quantum Life Luminescent Layer Efficiency Luminance Efficiency T90 Device Structure (cd/A) (cd/m2) (%) (hrs) OLED3 host material (thermally 45.1 5000 13.4 385 activated delayed fluorescence material 1-1, regulating host material niBr):phosphorescent dye OLED4 host material (thermally 57.2 5000 17.6 510 activated delayed fluorescence material 1-10, regulating host material CBP):phosphorescent dye OLED5 host material (thermally 51.0 5000 15.7 497 activated delayed fluorescence material 3-10, regulating host material TCTA):phosphorescent dye OLED6 host material (thermally 46.2 5000 14.2 387 activated delayed fluorescence material 2-5, regulating host material mCP:phosphorescent dye:phosphorescent dye OLED7 host material (thermally 54.6 5000 16.8 459 activated delayed fluorescence material 1-1, thermally activated delayed fluorescence material 3-1):phosphorescent dye OLED8 host material (thermally 63.4 5000 19.5 513 activated delayed fluorescence material 1-2, thermally activated delayed fluorescence material 2-4):phosphorescent dye OLED9 host material (thermally 48.7 5000 16.4 335 activated delayed fluorescence material 1-9, thermally activated delayed fluorescence material 3-4):phosphorescent dye OLED10 host material (thermally 38.9 5000 14.7 412 activated delayed fluorescence material 1-14, thermally activated delayed fluorescence material 3-7):phosphorescent dye

[0150] The above examples are merely preferred examples that are presented to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. The equivalent substitutions or alternations that are made by a person skilled in the art on the basis of the present invention all fall within the protection scope of the present invention. The protection scope of the present invention is limited by the claims.