Organic electroluminescence device, preparation method thereof and display apparatus

1. An organic electroluminescence device, comprising: an organic light emitting layer, wherein the organic light emitting layer comprises a host material, a sensitizer material, and a resonance thermally activated delayed fluorescent material;

the host material is a wide bandgap material;

the sensitizer material is an exciplex;

a singlet state energy level for the wide bandgap material is greater than a singlet state energy level for the exciplex, and a triplet state energy level for the wide bandgap material is greater than a triplet state energy level for the exciplex; and

a singlet state energy level for the exciplex is greater than a singlet state energy level for the resonance delayed fluorescent material, and a triplet state energy level for the exciplex is greater than a triplet state energy level for the resonance delayed fluorescent material.

2. The organic electroluminescence device according to claim 1 , wherein the resonance thermally activated delayed fluorescent material has a structure represented by Formula [1]:

wherein X is independently selected from one of B, P, P═O, P═S, SiR 1 ; R 1 is selected from hydrogen, substituted or unsubstituted C 1 -C 36 alkyl, substituted or unsubstituted C 6 -C 30 aryl, substituted or unsubstituted C 3 -C 30 heteroaryl;

A is selected from substituted or unsubstituted C 6 -C 30 aryl, substituted or unsubstituted C 3 -C 30 heteroaryl, substituted or unsubstituted C 6 -C 30 arylamino;

M 1 and M 2 are each independently selected from H, substituted or unsubstituted C 1 -C 36 alkyl, substituted or unsubstituted C 6 -C 30 aryl, substituted or unsubstituted C 3 -C 30 heteroaryl;

at least three of adjacent X, A, M 1 and M 2 are joined into a ring that comprises X;

a is an integer from 1 to 12;

when a substituent is presented in the above group, the substituents is individually and independently selected from one or more of halogen, cyano, C 1 -C 10 alkyl, C 2 -C 6 alkenyl, C 1 -C 6 alkoxy or thioalkoxy, C 6 -C 30 aryl and C 3 -C 30 heteroaryl.

3. The organic electroluminescence device according to claim 2 , wherein three of adjacent X, A, M 1 and M 2 are joined into a hexatomic ring comprising two heteroatoms; and

the heteroatoms are selected from two of B, P, Si, O, S, N, and Se.

4. The organic electroluminescence device according to claim 2 , wherein the ‘a’ in the formula [1] is an integer from 1 to 6.

5. The organic electroluminescence device according to claim 2 , wherein the resonance thermally activated delayed fluorescent material is a compound having one of the following general formulas:

wherein R is individually and independently selected from one or more of hydrogen, halogen, cyano, C 1 -C 10 alkyl, C 2 -C 6 alkenyl, C 1 -C 6 alkoxy or thioalkoxy, C 6 -C 30 aryl and C 3 -C 30 heteroaryl; and

Y is independently selected from O, S, and Se.

6. The organic electroluminescence device according to claim 5 , wherein the resonance thermally activated delayed fluorescent material is a compound having one of the structures shown in the following:

7. The organic electroluminescence device according to claim 1 , wherein the resonance thermally activated delayed fluorescent material has a molecular weight of 200-2000.

8. The organic electroluminescence device according to claim 1 , wherein the exciplex comprises an electron donor material and an electron acceptor material, the electron donor material being a component having characteristic of hole transporting and containing at least one of carbazolyl, arylamino, silyl, fluorenyl, dibenzothienyl, and dibenzofurylaryl;

and/or, the electron acceptor material being component having characteristic of electron transporting and containing at least one of pyridyl, pyrimidinyl, triazinyl, imidazolyl, phenanthroline, sulfone, heptazinyl, oxadiazolyl, cyano, and diphenyl.

9. The organic electroluminescence device according to claim 8 , wherein the weight ratio of the electron donor material to the electron acceptor material in the exciplex is 1:9-9:1.

10. The organic electroluminescence device according to claim 1 , wherein the wide bandgap material is a compound comprising at least one of carbazolyl, carbolinyl, spirofluorenyl, fluorenyl, silyl, and phosphonooxy.

11. The organic electroluminescence device according to claim 1 , wherein a percentage of the exciplex in the organic light emitting layer is 1 wt %-60 wt %;

a percentage of the wide bandgap material in the organic light emitting layer is 20 wt %-98.9 wt %; and

a percentage of the resonance thermally activated delayed fluorescent material in the organic light emitting layer is 0.1 wt %-20 wt %.

12. A display apparatus, comprising the organic electroluminescence device according to claim 1 .

13. A method for preparing an organic electroluminescence device, comprising the following steps: forming an organic light emitting layer by co-evaporation plating of a wide bandgap material, an electron donor material, an electron acceptor material, and a resonance thermally activated delayed fluorescent material.

14. The method for preparing an organic electroluminescence device according to claim 13 , wherein before the forming an organic light emitting layer, further comprising:

providing a substrate having an anode material thereon;

performing evaporation plating of a hole transporting region material onto the substrate to form a hole transporting region, wherein the evaporation plating is performed under conditions of 1×10 −5 ˜9×10 −3 Pa at an evaporation plating rate of 0.1 to 0.5 nm/s.

15. The method for preparing an organic electroluminescence device according to claim 13 , wherein after the forming an organic light emitting layer, the method further comprises: performing evaporation plating of an electron transporting region material on the organic light emitting layer to form an electron transporting region, wherein an evaporation plating rate is 0.1-0.5 nm/s.

16. The method for preparing an organic electroluminescence device according to claim 13 , further comprising a step of forming a cathode over the organic light emitting layer: performing evaporation plating of a cathode material to form a cathode, and an evaporation plating rate is 0.5 to 1 nm/s.