Materials and architectures for efficient harvesting of singlet and triplet excitons for white light emitting OLEDs

• US 20080102310A1
• Filed: 10/27/2006
• Published: 05/01/2008
• Est. Priority Date: 10/27/2006
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan), University of Southern California
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Forrest, Stephen, Thompson, Mark E.
• Granted Patent: US 8,945,722 B2
• Time in Patent Office: Days
• 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 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]

Abstract

The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

Claims

1. An organic light emitting device comprising:

a cathode,

an emissive region, and

an anode

wherein,

the emissive region comprises;

a fluorescent layer comprising a fluorescent emitting dopant, and a charge-transporting dopant in a host material, and

a phosphorescent layer comprising a phosphorescent emitting dopant, and a charge-transporting dopant in a host material.

2. The organic light emitting device of claim 1, wherein the charge-transporting dopant is a the hole-transporting dopant.

3. The organic light emitting device of claim 2, wherein the HOMO level of the hole-transporting dopant is above the HOMO level of the fluorescent emitting dopant and the HOMO level of the phosphorescent emitting dopant.

4. The organic light emitting device of claim 3, wherein the triplet energy of the hole-transporting dopant is higher than the triplet energy of the host material.

5. The organic light emitting device of claim 1, wherein the charge-transporting dopant is an the electron-transporting dopant.

6. The organic light emitting device of claim 5, wherein the LUMO level of the electron-transporting dopant is below the LUMO level of the fluorescent emitting dopant and the LUMO level of the phosphorescent emitting dopant.

7. The organic light emitting device of claim 6, wherein the triplet energy of the electron-transporting dopant is higher than the triplet energy of the host material.

8. The organic light emitting device of claim 1, wherein the device comprises a spacer layer between the fluorescent layer and the phosphorescent layer, and wherein the spacer layer comprises a charge-transporting dopant in a host material.

9. The organic light emitting device of claim 8, wherein the emissive region consists of the fluorescent layer, the spacer layer and the phosphorescent layer.

10. The organic light emitting device of claim 9, wherein the host material for the fluorescent layer, the host material for the phosphorescent layer and the spacer layer are comprised of the same material.

11. The organic light emitting device of claim 10, wherein the host material for the fluorescent layer, the host material for the phosphorescent layer and the spacer layer are comprised of CBP.

12. The organic light emitting device of claim 2, wherein the hole transporting dopant for the fluorescent layer, the hole transporting dopant for the phosphorescent layer and the hole transporting dopant for the spacer layer are comprised of the same material.

13. The device of claim 12, wherein the hole transporting dopant is.

14. The device of claim 1, wherein the fluorescent emitting dopant is a blue emitting fluorescent material.

15. The organic light emitting device of claim 1, wherein greater than about 75% of the excitons are generated in the fluorescent layer.

16. An organic light emitting device comprising:

a cathode,

an emissive region, and

an anode

wherein,

the emissive region comprises;

a fluorescent layer comprising a fluorescent emitting material as a dopant in a hole-transporting host material, and

a phosphorescent layer comprising a phosphorescent emitting material as a dopant in a hole-transporting host material.

17. The organic light emitting device of claim 16, wherein the device comprises a spacer layer between the fluorescent layer and the phosphorescent layer, and wherein the spacer layer comprises a hole-transporting host material.

18. The organic light emitting device of claim 17, wherein the emissive region consists of the fluorescent layer, the spacer layer and the phosphorescent layer.

19. The organic light emitting device of claim 18, wherein the hole-transporting host material for the fluorescent layer, the hole-transporting host material for the phosphorescent layer and the hole-transporting host material for the spacer layer are comprised of the same material.

20. The device of claim 16, wherein the fluorescent emitting material is a blue emitting fluorescent material.

21. The organic light emitting device of claim 16, wherein greater than about 75% of the excitons are generated in the fluorescent layer.