Organic electroluminescent device
View Patent ↗The organic electroluminescent device of the present invention has at least one organic compound layer containing a light-emitting layer between an anode and a cathode. The organic compound layer contains a fluorescent light-emitting compound emitting fluorescence at a time that voltage is applied and an amplifying agent. A phosphorescent light-emitting maximum wavelength of the amplifying agent is 500 nm or less, and the light emission at a time that voltage is applied is derived mainly from light emission of a fluorescent compound. In order to amplify intensity of emission at a time that voltage is applied It is preferable that the amplifying agent be capable of amplifying the number of singlet excitons generated at a time that voltage is applied.
1. An organic electroluminescent device having at least one organic compound layer containing a light-emitting layer between an anode and a cathode,
wherein the organic compound layer contains a hole-transporting layer, a light-emitting layer and an electron-transporting layer,
the light-emitting layer comprises a laminated structure formed by alternately laminating a layer containing at least one kind of fluorescent light-emitting compound emitting a fluorescent light at a time that voltage is applied and another layer containing at least one kind of amplifying agent, and
a phosphorescent light-emitting maximum wavelength of the amplifying agent is equal to or less than 500 nm, and light emission at a time that voltage is applied to the device comprises mainly the fluorescent light emitted from the fluorescent light-emitting compound,
wherein the laminated structure comprises at least four layers and at least one kind of the amplifying agent is represented by the following formula (1):
wherein R 11 to R 18 each represents a hydrogen atom or a substituent; L 11 represents a ligand; M 11 represents a transition metal ion; and n 11 is an integer of 1 to 3; n 12 is an integer of 0 to 4; and at least one of R 12 and R 14 is a fluorine atom, and
wherein a light-emitting maximum wavelength from the fluorescent light-emitting compound is 500 nm or less.
2. The organic electroluminescent device of claim 1 , wherein the amplifying agent is capable of amplifying a number of singlet excitons generated at a time that voltage is applied, thus amplifying the intensity of the light emission at a time that voltage is applied.
3. The organic electroluminescent device according to claim 1 , wherein a light-emitting layer contains at least one kind of host material, and a T 1 level of the host material (an energy level of a lowest excitation triplet state) is within a range of from 60 kcal/mol to 90 kcal/mol.
4. The organic electroluminescent device according to claim 1 , wherein a T 1 level of at least one layer formed between the light-emitting layer and the cathode is within a range of from 60 kcal/mol to 90 kcal/mol.
5. The organic electroluminescent device according to claim 1 , wherein the T 1 level of at least one layer formed between the light-emitting layer and the anode is within a range of from 60 kcal/mol to 90 kcal/mol.
6. The organic electroluminescent device of claim 1 , wherein R 13 is a substituent.
7. The organic electroluminescent device of claim 1 , wherein R 16 is a substituent.
8. The organic electroluminescent device according to claim 1 , wherein M 11 is an iridium ion.
9. The organic electroluminescent device according to claim 1 , wherein M 11 is a platinum ion.
10. The organic electroluminescent device according to claim 1 , wherein the fluorescent light-emitting compound is a fused aromatic compound.
11. The organic electroluminescent device according to claim 1 , wherein the organic compound layer contains an electron-transporting layer including a non-complex compound.
12. The organic electroluminescent device according to claim 1 , wherein R 12 and R 14 each represents a fluorine atom, M 11 represents an iridium ion, n 11 represents an integer of 2, and L 11 represents a nitrogen-containing heterocyclic ligand, a diketone ligand or a carboxylic ligand.
13. The organic electroluminescent device according to claim 12 , wherein L 11 represents a bidentate nitrogen-containing heterocyclic ligand.
14. The organic electroluminescent device according to claim 13 , wherein the bidentate nitrogen-containing heterocyclic ligand is a ligand having pyridine, pyrazine, pyrimidine, pyridazine, pyrrole, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole or thiadiazole.
15. The organic electroluminescent device according to claim 14 , wherein the bidentate nitrogen-containing heterocyclic ligand is a ligand having pyridine or pyrazole.
16. The organic electroluminescent device according to claim 15 , wherein the fluorescent light-emitting compound is a perylene.
17. The organic electroluminescent device according to claim 1 , wherein R 12 and R 14 each represents a fluorine atom, M 11 represents an iridium ion, n 11 represents an integer of 3, and n 12 represents an integer of 0.
18. The organic electroluminescent device according to claim 17 , wherein the fluorescent light-emitting compound is 2, 5, 8, 11-tetra(tert-butyl)perylene.
19. The organic electroluminescent device according to claim 1 , wherein at least 90% of the light-emission of the device is the fluorescent light emitted from the fluorescent light-emitting compound.
20. The organic electroluminescent device according to claim 1 , wherein the laminated structure has at least four layers formed by alternately laminating a layer containing at least one kind of fluorescent light-emitting compound emitting a fluorescent light when voltage is applied and another layer containing at least one kind of amplifying agent.
21. The organic electroluminescent device according to claim 1 , wherein a light-emitting maximum wavelength of the fluorescent light-emitting compound is equal to or less than 500 nm.
22. The organic electroluminescent device according to claim 1 , wherein at the least one kind of the amplifying agent is selected from the group consisting of