Organic light emitting devices having carrier blocking layers comprising metal complexes

• US 7,022,421 B2
• Filed: 08/23/2002
• Issued: 04/04/2006
• Est. Priority Date: 08/29/2001
• Status: Expired due to Term

• Current Assignee: Princeton University, University of Southern California
• Original Assignee: The Trustees of Princeton University (Princeton University), University of Southern California
• Inventors: Forrest, Stephen R., Thompson, Mark E., Adamovich, Vadim, Ren, Xiaofan, Alleyne, Bert, D'Andrade, Brian Wendell, Cordero, Steven
• Primary Examiner(s): GARRETT, DAWN L
• Application Number:
  US10/226,674
• Publication Number:
  US 20030068528A1
• Time in Patent Office: 1,320 Days
• Field of Search: 428/690, 428/917, 428/212, 313/504, 313/506, 427/66, 257/88
• US Class Current: 428/690
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/181 Electron blocking layers
• CPC Class Codes: H10K 85/10 Organic polymers or oligomers
• CPC Class Codes: H10K 85/111 comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• CPC Class Codes: H10K 85/1135 Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
• CPC Class Codes: H10K 85/30 Coordination compounds
• CPC Class Codes: H10K 85/321 Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/326 comprising gallium
• CPC Class Codes: H10K 85/341 Transition metal complexes, e.g. Ru(II)polypyridine complexes H10K85/331 takes precedence
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• 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
• CPC Class Codes: H10K 85/6565 Oxadiazole compounds
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Light emitting devices having blocking layers comprising one or more metal complexes are provided. The blocking layers may serve to block electrons, holes, and/or excitons. Preferably, the devices further comprise a separate emissive layer in which charge and/or excitons are confined. Metal complexes suitable for blocking layers can be selected by comparison of HOMO and LUMO energy levels of materials comprising adjacent layers in devices of the present invention.

Claims

1. A light emitting device comprising a blocking layer, wherein said blocking layer comprises a wide band-gap organic matrix into which a metal complex is doped, and wherein said wide band-gap organic matrix is doped with about 1 to about 50% by weight of metal complex.

2. A light emitting device comprising a blocking layer, wherein said blocking layer comprises a wide band-gap organic matrix into which a metal complex is doped, and wherein said organic matrix comprises octaphenyl cyclooctatetraene or oligophenyl.

3. A light emitting device comprising at least one blocking layer comprising a compound of formula:

wherein;

M is a metal atom;

X is N or CX′

where X′

is H, C₁–

C₂₀ alkyl, C₂–

C₄₀ mono- or poly alkenyl, C₂–

C₄₀ mono- or poly alkynyl, C₃–

C₈ cycloalkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo;

A is CH, CX′

, N, P, P(═

O), aryl or heteroaryl;

each R¹ and R² is, independently, H, C₁–

C₂₀ alkyl, C₂–

C₄₀ alkenyl, C₂–

C₄₀ alkynyl, C₃–

C₈ cycloalkyl, aryl, aralkyl, or halo;

or

R¹ and R², together with the carbon atoms to which they are attached, link to form a fused C_3,–

C₈ cycloalkyl or aryl group;

R³ is H, C₁–

C₂₀ alkyl, C₂–

C₄₀ alkenyl, C₂–

C₄₀ alkynyl, C₃–

C₈ cycloalkyl, aryl, aralkyl, or halo; and

n is 1 to 5.

4. The light emitting device of claim 3 wherein M is Al or Ga.

5. The light emitting device of claim 3 wherein R¹ and R² are linked to form a fused phenyl group.

6. The light emitting device of claim 3 wherein A is N.

7. A light emitting device comprising an emissive layer and an electron blocking layer, each of said layers having an anode side and a cathode side, wherein said anode side of said emissive layer is in contact with said cathode side of said electron blocking layer, wherein said electron blocking layer has a higher LUMO energy level than the LUMO energy level of said emissive layer and comprises at least one metal complex.

8. The light emitting device of claim 7 wherein the magnitude of the difference between the HOMO energy levels of said electron blocking layer and said emissive layer is less than the magnitude of the difference between said LUMO energy levels of said hole blocking layer and said emissive layer.

9. The light emitting device of claim 7 wherein said electron blocking layer has a HOMO energy level that is less than about 200 meV from the HOMO energy level of said emissive layer.

10. The light emitting device of claim 7 wherein said electron blocking layer consists essentially of said metal complex.

11. The light emitting device of claim 7 wherein said emissive layer comprises a host material doped with an emitter.

12. The light emitting device of claim 11 wherein said electron blocking layer comprises a wide-band gap organic matrix doped with said metal complex.

13. The light emitting device of claim 12 wherein said metal complex has a smaller band-gap than said matrix.

14. The light emitting device of claim 7 wherein the HOMO energy level of said metal complex is less than about 200 meV from the HOMO energy level of said emissive layer.

15. A light emitting device having the structure anode/hole transporting layer/electron blocking layer/emissive layer/electron transporting layer/cathode wherein said electron blocking layer comprises a wide band-gap organic matrix doped with a metal complex.

16. A method of confining holes to an emissive layer in a light emitting device, wherein said emissive layer comprises an anode side and a cathode side, and wherein said device comprises a blocking layer adjacent to said cathode side of said emissive layer, wherein said blocking layer has a lower HOMO energy level than the HOMO energy level of said emissive layer and comprises at least one transition metal complex, said method comprising, applying a voltage across said device.

17. The method of claim 16 wherein said blocking layer consists essentially of said metal complex.

18. The method of claim 16 wherein said blocking layer comprises wide band-gap organic matrix doped with said metal complex.

19. A method of confining holes to an emissive layer in a light emitting device, wherein said emissive layer comprises an anode side and a cathode side, and wherein said device comprises a blocking layer adjacent to said cathode side of said emissive layer, wherein said blocking layer has a lower HOMO energy level than the HOMO energy level of said emissive layer and comprises at least one six-coordinate metal complex, said method comprising, applying a voltage across said device.

20. A method of confining electrons to an emissive layer in a light emitting device, wherein said emissive layer comprises an anode side and a cathode side, and wherein said device comprises a blocking layer adjacent to said cathode side of said emissive layer, wherein said blocking layer has a higher LUMO energy level than the LUMO energy level of said emissive layer and comprises at least one metal complex, said method comprising, applying a voltage across said device.

21. The method of claim 20 wherein said blocking layer consists essentially of said metal complex.

22. The method of claim 20 wherein said blocking layer comprises matrix doped with said metal complex.

23. A method of fabricating a light emitting device, said method comprising depositing blocking layer onto a preexisting layer wherein said blocking layer comprises a compound of formula:

wherein;

M is a metal atom;

X is N or CX′

where X′

is H, C₁–

C₂₀ alkyl, C₂–

C₄₀ mono- or poly alkenyl, C₂–

C₄₀ mono- or poly alkynyl, C₃–

C₈ cycloalkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, or halo;

A is CH, CX′

, N, P, P(═

O), aryl or heteroaryl;

each R¹ and R² is, independently, H, C₁–

C₂₀ alkyl, C₂–

C₄₀ alkenyl, C₂–

C₄₀ alkynyl, C₃–

C₈ cycloalkyl, aryl, aralkyl, or halo;

or

R₁ and R₂, together with the carbon atoms to which they are attached, link to form a fused C₃–

C₈ cycloalkyl or aryl group;

R₃ is H, C₁–

C₂₀ alkyl, C₂–

C₄₀ alkenyl, C₂–

C₄₀ alkynyl, C₃–

–

C₈ cycloalkyl, aryl, aralkyl, halo; and

n is 1 to 5.

24. The method of claim 23 wherein said compound is Ga(pma)₃.