Electron-injecting layer providing a modified interface between an organic light-emitting structure and a cathode buffer layer

• US 6,172,459 B1
• Filed: 07/28/1998
• Issued: 01/09/2001
• Est. Priority Date: 07/28/1998
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Hung, Liang S., Tang, Ching W., Raychaudhuri, Pranab K.
• Primary Examiner(s): Patel, Nimeshkumar D.
• Assistant Examiner(s): Guharay, Karabi
• Application Number:
  US09/123,601
• Time in Patent Office: 896 Days
• Field of Search: 313/503, 313/504, 313/506, 428/917, 427/66
• US Class Current: 313/506
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 71/16 using physical vapour deposition [PVD], e.g. vacuum deposition or sputtering
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Abstract

An organic light-emitting device including a substrate; an anode disposed over the substrate; an organic light-emitting structure disposed over the anode; a cathode buffer layer disposed over the organic light-emitting structure and of a material selected to permit high energy deposition of a cathode; a cathode disposed over the cathode buffer layer; and an interfacial layer provided with an electron-injecting material between the organic light-emitting structure and the cathode buffer layer.

Claims

1. An organic light-emitting device comprising:

a) a substrate;

b) an anode disposed over the substrate;

c) an organic light-emitting structure disposed over the anode;

d) a cathode buffer layer disposed over the organic light-emitting structure and of a material selected to permit high energy deposition of a cathode, the cathode buffer layer including porphyrinic compounds;

e) a cathode disposed over the cathode buffer layer; and

f) an interfacial layer provided with an electron-injecting material between the organic light-emitting structure and the cathode buffer layer, wherein the cathode buffer layer includes porphyrinic compounds.

2. The organic light-emitting device of claim 1 wherein the substrate is an electrically insulative and light-transmissive substrate.

3. The organic light-emitting device of claim 2 wherein the anode is a light-transmissive anode having a work function greater than 4 electron volt (eV).

4. The organic light-emitting device of claim 3 wherein light is emitted from the organic light-emitting structure through the anode and the substrate when the anode is at a sufficient positive electrical potential with respect to the cathode.

5. The organic light-emitting device of claim 1 wherein the substrate is an optically opaque substrate.

6. The organic light-emitting device of claim 4 wherein the anode has a work function greater than 4 eV, and is electrically conductive.

7. The organic light-emitting device of claim 5 wherein light is emitted from the organic light-emitting structure through the cathode buffer layer and through a light-transmissive cathode when the anode is at a sufficient positive electrical potential with respect to the cathode.

8. The organic light-emitting device of claim 1 wherein the organic light-emitting structure is comprised of:

(i) an organic hole-transporting layer formed over the anode;

(ii) an organic light-emitting layer formed over the hole-transporting layer; and

(iii) an organic electron-transporting layer formed over the light-emitting layer.

9. The organic light-emitting device of claim 6 wherein the organic hole-transporting layer includes hole-transporting aromatic tertiary amine molecules.

10. The organic light-emitting device of claim 6 wherein the organic light-emitting layer includes a light-emitting metal chelated oxinoid compound.

11. The organic light-emitting device of claim 8 wherein the organic light-emitting layer further includes at least one dye capable of emitting light when dispersed in the light-emitting metal chelated oxinoid compound.

12. The organic light-emitting device of claim 6 wherein the electron-transporting layer includes a metal chelated oxinoid compound.

13. The organic light-emitting device of claim 1 wherein a selected porphyrinic compound is a phthalocyanine compound.

14. The organic light-emitting device of claim 12 wherein the phthalocyanine compound is a metal phthalocyanine.

15. The organic light-emitting device of claim 13 wherein a selected metal phthalocyanine is copper phthalocyanine.

16. The organic light-emitting device of claim 1 wherein the cathode buffer layer has a thickness in a range of 5-100 nm.

17. The organic light-emitting device of claim 15 wherein the cathode buffer layer is a light-transmissive layer.

18. The organic light-emitting device of claim 16 wherein the cathode buffer layer protects the organic light-emitting structure from damage during a high energy deposition of a cathode.

19. The organic light-emitting device of claim 1 wherein the cathode is formed by high energy sputter deposition.

20. The organic light-emitting device of claim 18 wherein the cathode is formed of a material which is selected to have a work function greater than 4 eV.

21. The organic light-emitting device of claim 19 wherein the cathode material is selected from the group consisting of elemental metals and electrically conductive metal oxides.

23. The organic light-emitting device of claim 21 wherein the electron-injecting material is selected from the Periodic Table groups IA and IIA.

24. The organic light-emitting device of claim 21 wherein the interfacial layer is formed by thermal evaporation deposition.

22. The organic light-emitting device of claim I wherein the interfacial layer is provided with an electron-injecting material which has a work function less than 4.0 eV.