LIGHT-EMITTING COMPONENT

• US 20090230844A1
• Filed: 02/22/2006
• Published: 09/17/2009
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Novaled AG
• Original Assignee: Novaled AG
• Inventors: Schwarz, Gregor, Birnstock, Jan, Pfeiffer, Martin, Murano, Sven
• Granted Patent: US 7,986,090 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers
• CPC Class Codes: H10K 85/611 Charge transfer complexes
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: H10K 85/649 Aromatic compounds comprising a hetero atom

Abstract

The invention relates to a light-emitting component, in particular organic light-emitting diode, having an electrode and a counterelectrode and an organic region—arranged between the electrode and the counterelectrode—with a light-emitting organic region, which comprises an emission layer and a further emission layer and which, upon application of an electrical voltage to the electrode and the counterelectrode, is formed in a manner emitting light in a plurality of colour ranges in the visible spectral range, optionally through to white light, in which case the emission layer comprises a fluorescent emitter which emits light predominantly in the blue or in the blue-green spectral range; the further emission layer comprises one or a plurality of phosphorescent emitters emitting light predominantly in the non-blue spectral range; a triplet energy for an energy level of a triplet state of the fluorescent emitter in the emission layer is greater than a triplet energy for an energy level of a triplet state of the phosphorescent emitter in the further emission layer; and an at least 5% proportion of the light generated in the light-emitting organic region is formed in the visible spectral range as fluorescent light from singlet states of the fluorescent emitter in the emission layer.

Claims

1. Light-emitting component, in particular organic light-emitting diode, having an electrode and a counterelectrode and an organic region—

arranged between the electrode and the counterelectrode—

with a light-emitting organic region (EM), which comprises an emission layer (EML1) and a further emission layer (EML2) and which, upon application of an electrical voltage to the electrode and the counterelectrode, is formed in a manner emitting light in a plurality of colour ranges in the visible spectral range, optionally through to white light, in which case;

the emission layer (EML1) comprises a fluorescent emitter which emits light predominantly in the blue or in the blue-green spectral range;

the further emission layer (EML2) comprises one or a plurality of phosphorescent emitters emitting light predominantly in the non-blue spectral range;

a triplet energy for an energy level of a triplet state of the fluorescent emitter in the emission layer (EML1) is greater than a triplet energy for an energy level of a triplet state of the phosphorescent emitter in the further emission layer (EML2); and

the light-emitting organic region is formed to deliver an at least 5% proportion of the light generated in the visible spectral range as fluorescent light from singlet states of the fluorescent emitter in the emission layer (EML1).

2. Light-emitting component according to claim 1, characterized in that the light-emitting organic region is formed to deliver an at least 10% proportion of the light generated in the visible spectral range as fluorescent light of the singlet states of the fluorescent emitter in the emission layer (EML1).

3. Light-emitting component according to claim 1, characterized in that the light generated in the light-emitting organic region is formed to deliver an at least 15% proportion of in the visible spectral range as fluorescent light of the singlet states of the fluorescent emitter in the emission layer (EML1).

4. Light-emitting component according to claim 1, characterized in that the light-emitting organic region is formed to deliver an at least 20% proportion of the light generated in the visible spectral range as fluorescent light of the singlet states of the fluorescent emitter in the emission layer (EML1).

5. Light-emitting component according to claim 1, characterized in that the light-emitting organic region is formed to deliver an at least 25% proportion of the light generated in the visible spectral range as fluorescent light of the singlet states of the fluorescent emitter in the emission layer (EML1).

6. Light-emitting component according to claim 1, characterized in that the emission layer (EML1) and the further emission layer (EML2) are formed in a manner adjoining one another.

7. Light-emitting component according to claim 1, characterized in that the emission layer (EML1) and the further emission layer (EML2) transport holes, and in that a distance between a surface of the emission layer (EML1) which faces the electrode formed as a cathode and a surface of the cathode which faces the emission layer (EML1) is less than a distance between a surface of the further emission layer (EML2) which faces the cathode and a surface of the cathode which faces the further emission layer (EML2).

8. Light-emitting component according to claim 1, characterized in that the emission layer (EML1) and the further emission layer (EML2) transport electrons, and in that a distance between a surface of the emission layer (EML1) which faces the counterelectrode formed as an anode and a surface of the anode which faces the emission layer (EML1) is less than a distance between a surface of the further emission layer (EML2) which faces the anode and a surface of the anode which faces the further emission layer (EML2).

9. Light-emitting component according to claim 1, characterized by the following features:

the light-emitting organic region (EM) comprises another emission layer (EML3) having one or a plurality of phosphorescent emitters emitting light predominantly in the non-blue spectral range;

the emission layer (EML1) is arranged between the further emission layer (EML2) and the other emission layer (EML3);

the further emission layer (EML2) transports electrons, a distance between a surface of the further emission layer (EML2) which faces the cathode and a surface of the cathode which faces the further emission layer (EML2) being less than a distance between a surface of the emission layer (EML1) which faces the cathode and a surface of the cathode which faces the emission layer (EML1), and also a distance between a surface of the other emission layer (EML3) which faces the cathode and a surface of the cathode which faces the other emission layer (EML3); and

the other emission layer (EML3) transports holes, a distance between a surface of the other emission layer (EML3) which faces the anode and a surface of the anode which faces the other emission layer (EML3) being less than a distance between a surface of the emission layer (EML1) which faces the anode and a surface of the anode which faces the emission layer (EML1), and also a distance between a surface of the further emission layer (EML2) which faces the anode and a surface of the anode which faces the further emission layer (EML2).

10. Light-emitting component according to claim 1, characterized in that a hole blocking layer is arranged between the emission layer (EML1) and the cathode, the hole blocking layer transporting electrons and an organic material of the hole blocking layer having an HOMO level which is at least approximately 0.3 eV lower than an HOMO level of the fluorescent emitter in the emission layer (EML1).

11. Light-emitting component according to claim 1, characterized in that an electron blocking layer is arranged between the emission layer (EML1) and the anode, the electron blocking layer transporting holes and an organic material of the electron blocking layer having an LUMO level which is at least approximately 0.3 eV higher than an LUMO level of the fluorescent emitter in the emission layer (EML1).

12. Light-emitting component according to claim 10, characterized in that a minimum energy of singlet excitons and of triplet excitons in the hole blocking layer or in the electron blocking layer is greater than a minimum energy of singlet excitons and of triplet excitons in the emission layer (EML1).

13. Light-emitting component according to claim 1, characterized in that the emission layer (EML1) and/or the further emission layer (EML2) and/or the other emission layer (EML3) are formed in multilayer fashion.

14. Light-emitting component according to claim 1, characterized in that the emission layer (EML1) has a thickness of between approximately 5 nm and approximately 50 nm.

15. Light-emitting component according to claim 1, characterized in that the light-emitting organic region (EM) is formed in a manner emitting white light, the or all of the phosphorescent emitters in the further emission layer (EML2) being emitters emitting light in the red, orange or yellow spectral range.

16. Light-emitting component according to claim 1, characterized in that the light-emitting organic region (EM) is formed in a manner emitting white light, the or all of the phosphorescent emitters in the further emission layer (EML2) being emitters emitting light in the red, orange or green spectral range.

17. Light-emitting component according to claim 1, characterized in that the light-emitting organic region (EM) is formed in a manner emitting white light, the or all of the phosphorescent emitters in the other emission layer (EML3) being emitters emitting light in the red, orange or yellow spectral range.

18. Light-emitting component according to claim 1, characterized in that the light-emitting organic region (EM) is formed in a manner emitting white light, the or all of the phosphorescent emitters in the other emission layer (EML3) being emitters emitting light in the red, orange or green spectral range.

19. Light-emitting component according to claim 1, characterized in that a respective doped organic layer is formed between the organic light-emitting region (EM) and the electrode and/or between the organic light-emitting region (EM) and the counterelectrode.

20. Light-emitting component according to claim 19, characterized in that the respective doped organic layer is a layer which is p-doped with an acceptor material or a layer which is n-doped with a donor material.

21. Light-emitting component according to claim 1, characterized in that the fluorescent emitter in the emission layer (EML1) is an organometallic compound or a complex compound with a metal having an ordinal number of less than 40.

22. Light-emitting component according to claim 1, characterized in that the fluorescent emitter in the emission layer (EML1) comprises an electron-attracting substituent from one of the following classes:

a) halogens such as fluorine, chlorine, iodine or bromine;

b) CN;

c) halogenated or cyano-substituted alkanes or alkenes, in particular trifluoromethyl, pentafluoroethyl, cyanovinyl, dicyanovinyl, tricyanovinyl;

d) halogenated or cyano-substituted aryl radicals, in particular pentafluorophenyl;

or

e) boryl radicals, in particular dialkylboryl, dialkylboryl having substituents on the alkyl groups, diarylboryl or diarylboryl having substituents on the aryl groups.

23. Light-emitting component according to claim 1, characterized in that the fluorescent emitter in the emission layer (EML1) comprises an electron-donating substituent of one of the following classes:

a) alkyl radicals such as methyl, ethyl, tert-butyl, isopropyl;

b) alkoxy radicals;

c) aryl radicals with or without substituents on the aryl, in particular tolyl and mesityl;

or

d) amino groups, in particular NH2, dialkylamine, diarylamine and diarylamine having substituents on the aryl.

24. Light-emitting component according to claim 1, characterized in that the fluorescent emitter in the emission layer (EML1) comprises a functional group having an electron acceptor property from one of the following classes:

a) oxadiazole

b) triazole

c) benzothiadiazoles

d) benzimidazoles and N-aryl-benzimidazoles

e) bipyridine

f) cyanovinyl

g) quinolines

h) quinoxalines

i) triarylboryl

j) silol units, in particular derivative groups of silacyclopentadiene

k) cyclooctatetraene

l) quinoid structures and ketones, including quinoid thiophene derivatives

m) pyrazolines

n) pentaaryl cyclopentadiene

o) benzothiadiazoles

p) oligo-para-phenyl with electron-attracting substituents, or

q) fluorenes and spiro-bifluorenes with electron-attracting substituents.

25. Light-emitting component according to claim 1, characterized in that the fluorescent emitter in the emission layer (EML1) comprises a functional group having an electron acceptor property from one of the following classes:

a) triarylamines

b) oligo-para-phenyl or oligo-meta-phenyl

c) carbazoles

d) fluorene or spiro-bifluorenes

e) phenylene-vinylene units

f) naphthalene

g) anthracene

h) perylene

i) pyrene or

j) thiophene.