High efficiency multi-color electro-phosphorescent OLEDs

• US 7,009,338 B2
• Filed: 05/13/2002
• Issued: 03/07/2006
• Est. Priority Date: 05/16/2001
• Status: Expired due to Term

• Current Assignee: The Trustees of Princeton University (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., D'Andrade, Brian
• Primary Examiner(s): Santiago, Mariceli
• Application Number:
  US10/144,419
• Publication Number:
  US 20020197511A1
• Time in Patent Office: 1,394 Days
• Field of Search: 313/504, 313/503, 313/506, 420/690, 420/917
• US Class Current: 313/504
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1092 containing sulfur as the only heteroatom
• CPC Class Codes: C09K 2211/185 of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd
• 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 50/157 between the light-emitting layer and the cathode
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

The present invention relates to efficient organic light emitting devices (OLEDs) doped with multiple light-emitting dopants, at least one dopant comprising a phosphorescent emitter, in a thin film emissive layer or layers. The present invention is directed to an efficient phosphorescent organic light emitting device utilizing a plurality of emissive dopants in an emissive region, wherein at least one of the dopants is a phosphorescent material. Thus, the present invention provides an organic light emitting device comprising an emissive region, wherein the emissive region comprises a host material, and a plurality of emissive dopants, wherein the emissive region is comprised of a plurality of bands and each emissive dopant is doped into a separate band within the emissive region, and wherein at least one of the emissive dopants emits light by phosphorescence.

Claims

1. An organic light emitting device comprising an ernissive region, wherein the emissive region comprises

a host material, and

a plurality of emissive dopants

wherein the emissive region is comprised of a plurality of bands and each emissive dopant is doped into a separate band within the emissive region, and wherein at least one of the emissive dopants emits light by phosphorescence from a triplet molecular excited state, and wherein a combined emission of the plurality of emissive dopants sufficiently spans the visible spectrum to give a white emission.

2. The device of claim 1, wherein the combined emission has a color rendering index of at least about 80.

3. The device of claim 1, wherein at least two of the bands comprising the emissive region are separated by an exciton blocking layer.

4. The device of claim 1, wherein the combined emission has a color rendering index of at least about 70.

5. The device of claim 1, wherein each emissive dopant emits by phosphorescence.

6. The device of claim 5, wherein the emissive dopants are phosphorescent organometallic compounds.

7. The device of claim 5, wherein the emissive dopants are arranged in the order of highest triplet energy, intermediate triplet energy, to lowest triplet energy.

8. The device of claim 5, wherein the emissive dopants are arranged in the order of highest triplet energy, lowest triplet energy, to intermediate triplet energy.

9. An organic light emitting device comprising

an anode;

a hole transporting layer;

an emissive region

an electron transporting layer; and

a cathode;

wherein the emissive region is comprised of a host material and a plurality of emissive dopants, and wherein the emissive region is comprised of a plurality of bands and each emissive dopant is doped into a separate band within the emissive region, and wherein at least one of the emissive dopants emits light by phosphorescence from a triplet molecular excited state, and wherein a combined emission of the plurality of emissive dopants sufficiently spans the visible spectrum to give a white emission.

10. The device of claim 9, wherein the combined emission has a color rendering index of at least about 80.

11. The device of claim 9, wherein at least two of the bands comprising the emissive region are separated by an exciton blocking layer.

12. The device of claim 9, wherein the device further comprises an exciton blocking layer.

13. The device of claim 9, wherein the device further comprises a hole injection layer.

14. The device of claim 9, wherein the combined emission has a color rendering index of at least about 70.

15. The device of claim 9, wherein each emissive dopant emits by phosphorescence.

16. The device of claim 15, wherein the emissive dopants are phosphorescent organometallic compounds.

17. The device of claim 15, wherein the emissive dopants are arranged in the order of highest triplet energy, intermediate triplet energy, to lowest triplet energy.

18. The device of claim 15, wherein the emissive dopants are arranged in the order of highest triplet energy, lowest triplet energy, to intermediate triplet energy.

19. An organic light emitting device comprising an anode, a cathode and an emissive region, wherein the emissive region is located between the anode and the cathode and the emissive region comprises

a host material, and

a plurality of emissive dopants,

wherein the emissive region is comprised of two or three bands and each emissive dopant is doped into a separate band within the emissive region, and wherein at least two of the emissive dopants emit light by phosphorescence from a triplet molecular excited state.

20. The device of claim 19, wherein at least two of the bands comprising the emissive region are separated by an exciton blocking layer.

21. The device of claim 19, wherein a combined emission of the plurality of emissive dopants sufficiently spans the visible spectrum to give a white emission.

22. The device of claim 21, wherein the combined emission has a color rendering index of at least about 80.

23. The device of claim 21, wherein the combined emission has a color rendering index of at least about 70.

24. The device of claim 19, wherein each emissive dopant emits by phosphorescence.

25. The device of claim 24, wherein the emissive dopants are phosphorescent organometallic compounds.

26. The device of claim 24, wherein the emissive dopants are arranged in the order of highest triplet energy, intermediate triplet energy, to lowest triplet energy.

27. The device of claim 24, wherein the emissive dopants are arranged in the order of highest triplet energy, lowest triplet energy, to intermediate triplet energy.

28. An organic light emitting device comprising an anode, a cathode and an emissive region, wherein the emissive region is located between the anode and the cathode and the emissive region comprises

a host material, and

a plurality of emissive dopants,

wherein the emissive region is comprised of a plurality of bands and each emissive dopant is doped into a separate band within the emissive region, and wherein at least one of the emissive dopants emits light by phosphorescence from a triplet molecular excited state, and wherein a combined emission of the plurality of emissive dopants sufficiently spans the visible spectrum to give a white emission.

29. The device of claim 28, wherein at least two of the bands comprising the emissive region are separated by an exciton blocking layer.

30. The device of claim 28, wherein the combined emission has a color rendering index of at least about 80.

31. The device of claim 30, wherein the combined emission has a color rendering index of at least about 70.

32. The device of claim 30, wherein each emissive dopant emits by phosphorescence.

33. The device of claim 28, wherein the emissive dopants are phosphorescent organometallic compounds.

34. The device of claim 33, wherein the emissive dopants are arranged in the order of highest triplet energy, intermediate triplet energy, to lowest triplet energy.

35. The device of claim 33, wherein the emissive dopants are arranged in the order of highest triplet energy, lowest triplet energy, to intermediate triplet energy.