Light-emissive device having co-evaporated cathode

• US 8,018,148 B2
• Filed: 07/14/2008
• Issued: 09/13/2011
• Est. Priority Date: 12/08/1998
• Status: Expired due to Fees

• Current Assignee: Cambridge Display Technology Limited (Sumitomo Chemical Company Limited)
• 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): Roy; Sikha
• Application Number:
  US12/172,721
• Publication Number:
  US 20090033214A1
• Time in Patent Office: 1,156 Days
• Field of Search: 313/504, 313/506, 445/24, 445/25
• 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: H10K 59/8052 Cathodes
• CPC Class Codes: H10K 59/875 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 59/8792 comprising light absorbing layers, e.g. black layers
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A light-emissive device comprising: 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 including a light absorbent layer comprising graphite and/or a fluoride or oxide of a low work function metal.

Claims

1. A method of manufacturing a light-emissive device, the method comprising:

depositing an anode;

depositing a light-emissive region; and

depositing a cathode by co-evaporating barium metal and a fluoride or oxide of a low work function metal so as to reduce reflectivity of the cathode.

2. A method according to claim 1, wherein the fluoride or oxide of a low work function metal is a fluoride.

3. A method according to claim 1, wherein depositing the cathode further comprises depositing aluminum.

4. A method according to claim 3, wherein the aluminum forms a separate layer.

5. A light-emissive device comprising:

an anode;

a light-emissive region; and

a low or non-reflective cathode comprising a mixture of co-evaporated barium metal and a fluoride or oxide of a low work function metal.

6. A light-emissive device according to claim 5, wherein the fluoride or oxide of a low work function metal is a fluoride.

7. A light-emissive device according to claim 5, wherein the cathode further comprises aluminum.

8. A light-emissive device according to claim 7, wherein the aluminum forms a separate layer.