Organic light emitting device structure for obtaining chromaticity stability

• US 20050006642A1
• Filed: 01/20/2004
• Published: 01/13/2005
• Est. Priority Date: 07/10/2003
• Status: Active Grant

• Current Assignee: Universal Display Corporation
• Original Assignee: Universal Display Corporation
• Inventors: Tung, Yeh-Jiun, Ngo, Tan
• Granted Patent: US 7,211,823 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• 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 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• 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 present invention relates to organic light emitting devices (OLEDs). The devices of the present invention are efficient white or multicolored phosphorescent OLEDs which have a high color stability over a wide range of luminances. The devices of the present invention comprise an emissive region having at least two emissive layers, with each emissive layer comprising a different host and emissive dopant, wherein at least one of the emissive dopants emits by phosphorescence.

Claims

1. An organic light emitting device comprising:

an anode;

an emissive region; and

a cathode,

wherein the emissive region comprises;

a first emissive layer, comprising a first host material and a first emissive material, and

a second emissive layer in physical contact with the first emissive layer and comprising a second host material and a second emissive material, and wherein;

the first emissive layer is nearer to the anode than the second emissive layer, and

at least one of the first emissive material or the second emissive material is a phosphorescent emissive material.

2. The organic light emitting device of claim 1, wherein the contact between the first emissive layer and the second emissive layer provides an electron injection barrier, a hole injection barrier, or both.

3. The organic light emitting device of claim 2, wherein the contact between the first emissive layer and the second emissive layer provides an electron injection barrier.

4. The organic light emitting device of claim 3, wherein the first emissive layer has a lower electron mobility than the second emissive layer.

5. The organic light emitting device of claim 2, wherein the contact between the first emissive layer and the second emissive layer provides a hole injection barrier.

6. The organic light emitting device of claim 5, wherein the second emissive layer has a lower hole mobility than the first emissive layer.

7. The organic light emitting device of claim 1, wherein the device further comprises a blocking layer.

8. The organic light emitting device of claim 1, wherein the emissive region further comprises an additional emissive layer.

9. The organic light emitting device of claim 1, wherein the first host material is mCP and the second host material is TPBi.

10. The organic light emitting device of claim 1, wherein the first emissive material and the second emissive material are a phosphorescent emissive materials.

11. The organic light emitting device of claim 1, wherein the cathode is in physical contact with the emissive region.

12. The organic light emitting device of claim 1, wherein the device is capable of an external quantum efficiency of at least about 10%.

13. The organic light emitting device of claim 8, wherein the additional emissive region is disposed between the first emissive region and the anode.

14. The organic light emitting device of claim 13, wherein the first emissive layer comprises Ir(F₂CNppy)₂(pic) in mCP, the second layer comprises Ir(pq)₂(acac), and the additional emissive layer comprises Ir(Ph-ppy)₃ in mCP.

15. An organic light emitting device comprising:

an emissive region disposed between and electrically connected to an anode and a cathode,

wherein the emissive region comprises;

a first emissive layer, comprising a first host material and a first emissive material, and

a second emissive layer in physical contact with the first emissive layer and comprising a

second host material and a second emissive material,

wherein;

the contact between the first emissive layer and the second emissive layer provides an electron injection barrier, a hole injection barrier, or both,

the first emissive layer is nearer to the anode than the second emissive layer,

at least one of the first emissive material or the second emissive material is a phosphorescent emissive material, and

wherein the device emits with CIE x,y-coordinates that vary less than about 0.04 over the luminance range of about 1000 cd/m² to about 20,000 cd/m².

16. The organic light emitting device of claim 15, wherein the contact between the first emissive layer and the second emissive layer provides an electron injection barrier.

17. The organic light emitting device of claim 16, wherein the first emissive layer has a higher LUMO than the second emissive layer.

18. The organic light emitting device of claim 16, wherein the first emissive layer has a lower electron mobility than the second emissive layer.

19. The organic light emitting device of claim 15, wherein the contact between the first emissive layer and the second emissive layer provides a hole injection barrier.

20. The organic light emitting device of claim 19, wherein the second emissive layer has a lower HOMO than the first emissive layer.

21. The organic light emitting device of claim 16, wherein the second emissive layer has a lower hole mobility than the first emissive layer.

22. The organic light emitting device of claim 15, wherein the emissive region further comprises an additional emissive layer.

23. The organic light emitting device of claim 15, wherein the device emits with CIE x,y-coordinates that vary less than about 0.02 over the luminance range of about 1000 cd/m² to about 20,000 cd/m².

24. The organic light emitting device of claim 23, wherein the device emits with CIE x,y-coordinates that vary less than about 0.01 over the luminance range of about 1000 cd/m² to about 20,000 cd/m².

25. The organic light emitting device of claim 15, wherein the device emits with CIE x,y-coordinates that vary less than about 0.04 over the luminance range of about 50 cd/m² to about 50,000 cd/m².

26. The organic light emitting device of claim 25, wherein the device emits with CIE x,y-coordinates that vary less than about 0.02 over the luminance range of about 50 cd/m² to about 50,000 cd/m².

27. The organic light emitting device of claim 26, wherein the device emits with CIE x,y-coordinates that vary less than about 0.01 over the luminance range of about 50 cd/m² to about 50,000 cd/m².

28. The organic light emitting device of claim 15, wherein the first emissive material and the second emissive material are phosphorescent emissive materials.

29. The organic light emitting device of claim 15, wherein the first host material is a high energy gap material and the first emissive material is a phosphorescent blue-emitting material.

30. The organic light emitting device of claim 15, wherein the second host material is a high energy gap material and the second emissive material is a phosphorescent blue-emitting material.

31. The organic light emitting device of claim 15, wherein the first host material is mCP and the second host material is CBP.

32. An organic light emitting device comprising an emissive region disposed between and electrically connected to an anode and a cathode, wherein the emissive region comprises:

a first emissive layer, comprising a first host material and a first emissive material, and

a second emissive layer comprising a second host material and a second emissive material, and

a blocking layer between and in contact with the first emissive layer and the second emissive layer,

wherein;

the blocking layer is an electron blocking layer or a hole blocking layer, and

at least one of the first emissive material or the second emissive material is a phosphorescent emissive material.

33. The organic light emitting device of claim 32, wherein the blocking layer is an electron blocking layer.

34. The organic light emitting device of claim 32, wherein the blocking layer is a hole blocking layer.

35. The organic light emitting device of claim 32, wherein the second host material is a high energy gap material and the second emissive material is a phosphorescent blue-emitting material.