Phosphorescent oled having double exciton-blocking layers

• US 8,034,465 B2
• Filed: 06/20/2007
• Issued: 10/11/2011
• Est. Priority Date: 06/20/2007
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Pellow, Cynthia A., Tyan, Yuan-Sheng, Liao, Liang-Sheng, Ren, Xiaofan
• Primary Examiner(s): Shosho; Callie
• Assistant Examiner(s): Wilson; Michael H
• Application Number:
  US11/765,598
• Publication Number:
  US 20080315753A1
• Time in Patent Office: 1,574 Days
• Field of Search: None
• US Class Current: 428/690
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1011 Condensed systems
• CPC Class Codes: C09K 2211/1014 bridged by heteroatoms, e.g. N, P, Si or B
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1044 containing two nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/1048 with oxygen
• CPC Class Codes: C09K 2211/1059 containing three nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/185 of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd
• CPC Class Codes: C09K 2211/186 of the light metals other than alkali metals and alkaline earth metals, i.e. Be, Al or Mg
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• 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: Y10S 428/917 Electroluminescent

Abstract

An organic light-emitting device comprising an anode; a cathode; a hole-transporting layer disposed between the anode and the cathode; a phosphorescent light-emitting layer disposed between the hole-transporting layer and the cathode, wherein the phosphorescent light-emitting layer includes at least one host and at least one phosphorescent dopant; a first exciton-blocking layer disposed between the hole-transporting layer and the phosphorescent light-emitting layer; wherein the first exciton-blocking layer has a triplet energy greater than the triplet energy of the host in the phosphorescent light-emitting layer; and a second exciton-blocking layer disposed between the first exciton-blocking layer and the phosphorescent light-emitting layer, wherein the second exciton-blocking layer is in contact with the phosphorescent light-emitting layer, and wherein the second exciton-blocking layer has a triplet energy less than the triplet energy of the first exciton-blocking layer.

Claims

1. An organic light-emitting device comprising:

a. an anode;

b. a cathode;

c. a hole-transporting layer disposed between the anode and the cathode;

d. a phosphorescent light-emitting layer disposed between the hole-transporting layer and the cathode, wherein the phosphorescent light-emitting layer includes at least one host and at least one phosphorescent dopant;

e. a first exciton-blocking layer disposed between the hole-transporting layer and the phosphorescent light-emitting layer;

wherein the first exciton-blocking layer includes a first exciton-blocking material that has a triplet energy greater than the triplet energy of the host in the phosphorescent light-emitting layer; and

f. a second exciton-blocking layer disposed between the first exciton-blocking layer and the phosphorescent light-emitting layer, wherein the second exciton-blocking layer is in contact with the phosphorescent light-emitting layer, and wherein the second exciton-blocking layer includes a second exciton-blocking material that has a triplet energy less than the triplet energy of the first exciton-blocking material,

wherein the first exciton-blocking material and the second exciton-blocking material are different carbazole derivatives represented by formula (J);

2. The organic light-emitting device of claim 1, wherein the second exciton-blocking layer enhances the exciton-blocking effect and eliminates light emission from the hole-transporting layer.

3. The organic light-emitting device of claim 1 wherein the second exciton-blocking layer has a triplet energy greater than the triplet energy of the dopant in the phosphorescent light-emitting layer.

4. The organic light-emitting device of claim 1 wherein the second exciton-blocking layer has an oxidation potential not less than the oxidation potential of the first exciton-blocking layer.

5. The organic light-emitting device of claim 1 wherein the second exciton-blocking layer has an oxidation potential less than the oxidation potential of the host in the phosphorescent light-emitting layer.

6. The organic light-emitting device of claim 1 wherein the second exciton-blocking layer has a reduction potential less than the reduction potential of the host in the phosphorescent light-emitting layer.

7. The organic light-emitting device of claim 1 wherein the first exciton-blocking layer and the second exciton-blocking layer each has a thickness in the range of from 1 nm to 50 nm.

8. The organic light-emitting device of claim 1 wherein the first exciton-blocking layer and the second exciton-blocking layer each has a thickness in the range of from 2 nm to 20 nm.

9. The organic light-emitting device of claim 1 wherein the carbazole derivative in the first exciton-blocking layer is selected from:

10. The organic light-emitting device of claim 1 wherein the carbazole derivative in the second exciton-blocking layer is selected from 9,9′

41,′

-biphenyl]-4,4′

-diylbis-9H-carbazole (CBP), 9,9′

-(2,2′

-dimethyl[1,1′

-biphenyl]-4,4′

-diyl)bis-9H-carbazole (CDBP) and 9,9′

-(1,4-phenylene)bis-9H-carbazole.

11. The organic light-emitting device of claim 1 wherein the host in the phosphorescent light-emitting layer includes an electron-transporting material.

12. The organic light-emitting device of claim 11 wherein the electron-transporting materials is a benzazole derivative represented by structural formula (K):

13. The organic light-emitting device of claim 12 wherein the benzazole derivative includes 2,2′

,2″

-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole] (TPBI).

14. The organic light-emitting device of claim 11 wherein the electron-transporting material is an aluminum or gallium complex represented by Formula (R-a):

15. The organic light-emitting device of claim 14 wherein the aluminum or gallium complex includes aluminum(III) bis(2-methyl-8-hydroxyquinoline)-4-phenylphenolate [alias, Balq] and gallium oxine [alias, tris(8-quinolinolato)gallium(III).

16. The organic light-emitting device of claim 1 wherein the device includes two light-emitting layers.

17. The organic light-emitting device of claim 16 wherein the two light-emitting layers emit light of substantially different colors.

18. The OLED of claim 1 wherein the phosphorescent dopant in the phosphorescent light-emitting layer is selected from tris(1-phenylisoquinoline) iridium (III) (Ir(piq)₃), Ir(ppy)₂(cou1), Ir(cou2)₂ppy, or tris(2-phenylpyridine) iridium (III) (Ir(ppy)₃).

19. The organic light-emitting device of claim 1 that produces white light.