Display devices with reflectivity-influencing electrode

• US 7,400,090 B1
• Filed: 12/07/1999
• Issued: 07/15/2008
• Est. Priority Date: 12/08/1998
• Status: Expired due to Fees

• Current Assignee: IPIFS Guarantee Corp.
• Original Assignee: Cambridge Display Technology Limited (Sumitomo Chemical Company Limited)
• Inventors: Burroughes, Jeremy Henley, Berger, Paul, Carter, Julian Charles, Heeks, Stephen Karl
• Primary Examiner(s): Guharay; Karabi
• Assistant Examiner(s): Roy; Sikha
• Application Number:
  US09/857,698
• Time in Patent Office: 3,143 Days
• Field of Search: 313/503, 313/506, 313/112
• US Class Current: 313/506
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/865 comprising light absorbing layers, e.g. light-blocking layers
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A light-emissive device including: a light-emissive region (12); a first electrode (10) located on a viewing side of the light-emissive region for injecting charge carriers of a first type; and a second-electrode (11) located on a non-viewing side of the light-emissive region for injecting charge carriers of a second type; and wherein there is a reflectivity-influencing structure (13) located on the non-viewing side of the light-emissive region and having a light absorbent layer including graphite and/or a fluoride or oxide of a low work function metal.

Claims

1. A light-emissive device comprising:

a light-emissive region;

a first electrode located on a viewing side of the light-emissive region for injecting charge carriers of a first type; and

a second electrode comprising a charge injecting layer and a reflectivity-influencing structure, the reflectivity-influencing structure being located on an opposite side of the charge injecting layer from the light-emissive region;

and including a light absorbent layer comprising an inorganic compound comprising a fluoride or oxide of a metal having a work function of 3.5 ev or less.

2. A light-emissive device as claimed in claim 1, wherein the first electrode is at least partially light-transmissive.

3. A light-emissive device as claimed in claim 1, wherein the second electrode further comprises a layer of electrically conductive material and the reflectivity-influencing structure is located between the layer of electrically conductive material and the charge injecting layer.

4. A light-emissive device as claimed in claim 3, wherein the charge injecting layer is at least partially light-transmissive.

5. A light-emissive device as claimed in claim 3, wherein the thickness of the charge-injecting layer is less than 30 nm.

6. A light-emissive device as claimed in claim 3, wherein the charge injecting layer comprises a fluoride or oxide of a low work function metal.

7. A light-emissive device as claimed in claim 6, wherein the the layer of electrically conductive material comprises aluminum.

8. A light-emissive device as claimed in claim 1, wherein the reflectivity-influencing structure is effective to absorb light emitted from the light-emissive region that reaches it through the charge injecting layer and/or incident light.

9. A light-emissive device as claimed in claim 1, wherein the presence of the reflectivity-influencing structure renders the second electrode substantially non-reflective to light emitted from the light-emissive region and/or incident light.

10. A light-emissive device as claimed n claim 1, wherein the light emissive region comprises an organic light-emissive material.

11. A light-emissive device as claimed in claim 1, wherein the light-emissive region comprises a polymer light-emissive material.

12. A light-emissive device as claimed in claim 1, wherein the light-emissive region comprises a conjugated polymer material.

13. A light-emissive device as claimed in claim 1, wherein the reflectivity-influencing structure is electrically conductive.