Multiple dopant emissive layer OLEDs

• US 8,330,351 B2
• Filed: 04/19/2007
• Issued: 12/11/2012
• Est. Priority Date: 04/20/2006
• Status: Active Grant

• Current Assignee: Universal Display Corporation
• Original Assignee: Universal Display Corporation
• Inventors: Adamovich, Vadim, Weaver, Michael S., Lu, Min-Hao Michael
• Primary Examiner(s): Bowman, Mary Ellen
• Application Number:
  US12/225,318
• Publication Number:
  US 20100244725A1
• Time in Patent Office: 2,063 Days
• Field of Search: 313/504, 313/506, 428/690, 257/102, 438/45
• 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 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom

Abstract

An organic light emitting device comprising, an anode, a cathode, and an emissive layer, located between the anode and the cathode, of a host compound, a first compound capable of phosphorescent emission at room temperature, and a second compound capable of phosphorescent emission at room temperature is provided. At least 95 percent of emission from the device is produced from the second compound when an appropriate voltage is applied across the anode and cathode.

Claims

1. An organic light emitting device, comprising an anode, a cathode, and an emissive layer, wherein the emissive layer is located between the anode and the cathode, an electron transport layer between the cathode and the emissive layer, and the emissive layer comprises:

a host compound;

a first compound capable of green or blue phosphorescent emission at room temperature; and

a second compound capable of red phosphorescent emission at room temperature present in an amount of at least 3 weight %;

wherein there is at least one voltage at which at least 95 percent of the emission from the device is produced from the second compound with a luminance of at least 10 cd/m², when the at least one voltage is applied across the anode and the cathode.

2. The organic light emitting device of claim 1, wherein the first compound is a charge carrying compound.

3. The organic light emitting device of claim 1, wherein the first compound is an electron carrying compound.

4. The organic light emitting device of claim 1, wherein the first compound is a hole carrying compound.

5. The organic light emitting device of claim 1, wherein the device has a CIE that is substantially the same as that of a second device, wherein the second device differs from the device only in that the second device has an emissive layer that does not contain the first compound.

6. The organic light emitting device of claim 1, wherein the device has an external quantum efficiency greater than that of a second device, wherein the second device differs from the device only in that the second device has an emissive layer that does not contain the first compound.

7. The organic light emitting device of claim 6, wherein the second device has a doping percentage of the second compound equivalent to that of the second compound of the device.

8. The organic light emitting device of claim 1, wherein the device has a lifetime greater than that of a second device, wherein the second device differs from the device only in that the second device has an emissive layer that does not contain the first compound.

9. The organic light emitting device of claim 8, wherein the lifetime of the device is at least 3 times that of the second device.

10. The organic light emitting device of claim 8, wherein the lifetime of the device is from about 3 to about 4 times that of the second device.

11. The organic light emitting device of claim 1, wherein the first compound is present in an amount of from about 3.5 to about 40 mole percent, based on the emissive layer.

12. The organic light emitting device of claim 1, wherein the first compound is present in an amount of about 15 mole percent, based on the emissive layer.

13. The organic light emitting device of claim 1, wherein at least 99 percent of emission from the device is produced from the second compound when the at least one voltage is applied across the anode and cathode.

14. The organic light emitting device of claim 1, wherein substantially all emission from the device is produced from the second compound when the at least one voltage is applied across the anode and cathode.

15. The organic light emitting device of claim 1, wherein, when the first compound emits, the emission is a green phosphorescent emission.

16. The organic light emitting device of claim 1, wherein, when the first compound emits, the emission is a blue phosphorescent emission.

17. The organic light emitting device of claim 1, wherein at least one of the first and second compounds is an organometallic compound.

18. The organic light emitting device of claim 1, wherein the first compound is Iridium(III)tris[2-(biphenyl-3-yl)-4-tert-butylpyridine], and the second compound is Bis[5-Phenyl-3′

-methyl(2-phenylquinoline)]iridium(III) acetylacetonate.

19. The organic light emitting device of claim 1, wherein the first compound is Iridium(III)tris(3-methyl-2-phenylpyridine), and the second compound is Bis[3′

-methyl(2-phenylquinoline)]iridium(III) acetylacetonate.

20. The organic light emitting device of claim 1, wherein the first compound has a HOMO level between the HOMO level of the host and the HOMO level of the second compound.

21. The organic light emitting device of claim 1, wherein the first compound has a LUMO level between the LUMO level of the host and the LUMO level of the second compound.

22. A process for making the organic light emitting device of claim 1, comprising solution depositing the emissive layer.

23. A process for making the organic light emitting device of claim 1, comprising vapor depositing the emissive layer.

25. The organic light emitting device of claim 1, wherein the device lacks a blocking layer between the emissive layer and the electron transport layer.

24. A method for producing light emission from an organic light emitting device, comprising:

obtaining an organic light emitting device comprising an anode, a cathode, and an emissive layer, wherein the emissive layer is located between the anode and the cathode, an electron transport layer between the cathode and the emissive layer, and the emissive layer comprises;

a host compound;

a first compound capable of green or blue phosphorescent emission at room temperature; and

a second compound capable of red phosphorescent emission at room temperature present in an amount of at least 3 weight %; and

applying a voltage across the anode and the cathode sufficient to produce emission with a luminance of at least 10 cd/m² from the device, wherein at least 95 percent of the emission is produced from the second compound.

26. The method of claim 24, wherein the device lacks a blocking layer between the emissive layer and the electron transport layer.