Tandem OLED having an organic intermediate connector

• US 20060188745A1
• Filed: 02/23/2005
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Hatwar, Tukaram K., Liao, Liang-Sheng, Ricks, Michele L., Slusarek, Wojciech K., Comfort, Dustin L.
• Granted Patent: US 7,494,722 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 85/611 Charge transfer complexes
• 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

A tandem OLED includes an anode and a cathode. The OLED also includes at least two electroluminescent units disposed between the anode and the cathode, wherein each of the electroluminescent units includes at least one hole -transporting layer and one organic light-emitting layer. An intermediate connector is disposed between adjacent electroluminescent units, wherein the intermediate connector includes an n-doped organic layer and an electron-accepting layer, the electron-accepting layer being disposed closer to the cathode than the n-doped organic layer, and wherein the electron-accepting layer includes one or more organic materials, each having a reduction potential greater than −0.5 V vs. a Saturated Calomel Electrode, and wherein the one or more organic materials constitute more than 50% by volume of the electron-accepting layer.

Claims

1. A tandem OLED comprising:

a) an anode;

b) a cathode;

c) at least two electroluminescent units disposed between the anode and the cathode, wherein each of the electroluminescent units includes at least one hole-transporting layer and one organic light-emitting layer; and

d) an intermediate connector disposed between adjacent electroluminescent units, wherein the intermediate connector includes an n-doped organic layer and an electron-accepting layer, the electron-accepting layer being disposed closer to the cathode than the n-doped organic layer, and wherein the electron-accepting layer includes one or more organic materials, each having a reduction potential greater than −

0.5 V vs. a Saturated Calomel Electrode, and wherein the one or more organic materials constitutes more than 50% by volume of the electron-accepting layer.

2. The tandem OLED of claim 1 wherein the one or more organic materials have a reduction potential greater than −

0.1 V vs. a Saturated Calomel Electrode.

3. The tandem OLED of claim 1 wherein there are three electroluminescent units and two intermediate connectors, each intermediate connector disposed between adjacent electroluminescent units.

4. The tandem OLED of claim 1 wherein the electron-accepting layer has a thickness range of from 3 nm to 100 nm.

5. The tandem OLED of claim 1 wherein the one or more organic materials in the electron-accepting layer include a chemical compound of the following formula:

6. The tandem OLED of claim 5 wherein the one or more organic materials in the electron-accepting layer include

7. The tandem OLED of claim 1 wherein the one or more organic materials in the electron-accepting layer include a chemical compound of the following formula:

8. The tandem OLED of claim 7 wherein the one or more organic materials in the electron-accepting layer include

9. The tandem OLED of claim 1 wherein the one or more organic materials in the electron-accepting layer includes a compound having a molecular weight greater than 350.

10. The tandem OLED of claim 9 wherein the compound constitutes more than 90% by volume of the electron-accepting layer.

11. The tandem OLED of claim 1 wherein the intermediate connectors are different.

12. The tandem OLED of claim 1 wherein the electroluminescent units individually emit red, green, blue, or white light.

13. The tandem OLED of claim 1 wherein the n-type doped organic layer contains one electron-transporting material and at least one n-type dopant.

14. The tandem OLED of claim 13 wherein the electron-transporting material includes metal chelated oxinoid compounds, butadiene derivatives, heterocyclic optical brighteners, triazines, hydroxyquinoline derivatives, benzazole derivatives, phenanthroline derivatives, or silole derivatives, or combinations thereof.

15. The tandem OLED of claim 13 wherein the electron-transporting material includes tris(8-hydroxyquinoline)aluminum (Alq), 4,7-diphenyl-1,10-phenanthroline (Bphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), or 2,2′

-[1,1′

-biphenyl]-4,4′

-diylbis[4,6-(p-tolyl)-1,3,5-triazine] (TRAZ), or combinations thereof.

16. The tandem OLED of claim 13 wherein the n-type dopant includes alkali metals, alkali metal compounds, alkaline earth metals, alkaline earth metal compounds, or rare earth metal, or combinations thereof.

17. The tandem OLED of claim 13 wherein the n-type dopant includes Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, La, Ce, Nd, Sm, Eu, Th, Dy, or Yb, or combinations thereof.

18. The tandem OLED of claim 1 wherein the intermediate connector further comprises a p-doped organic layer in contact with the electron-accepting layer, the p-doped organic layer being disposed closer to the cathode than the electron-accepting layer.

19. The tandem OLED of claim 1 wherein the intermediate connector further comprises an interfacial layer disposed between the n-type doped organic layer and the electron-accepting layer, such interfacial layer including a metal or metal compound.

20. An OLED solid-state lighting source comprising the tandem OLED of claim 1.