Polymer-based electroluminescent device with improved stability

• US 5,629,389 A
• Filed: 06/06/1995
• Issued: 05/13/1997
• Est. Priority Date: 06/06/1995
• Status: Expired due to Term

• Current Assignee: InnoLux Corporation
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Roitman, Daniel B., Sheats, James R., Hueschen, Mark R.
• Primary Examiner(s): MORRIS, TERREL H
• Application Number:
  US08/463,141
• Time in Patent Office: 707 Days
• Field of Search: 525/534, 525/540, 362/800, 257/80, 257/83, 252/500
• US Class Current: 525/534
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• 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 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 85/114 Poly-phenylenevinylene; Derivatives thereof
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An improved electroluminescent device which includes a hole injection electrode, an electron injection electrode, and an electroluminescent layer located between the hole and electron injection electrodes. The electroluminescent layer includes an organic polymer and a hindered phenolic additive in a concentration greater than 4% by weight. The preferred organic polymer is a derivative of PPV. The preferred hindered phenolic additives are and 2,4,6 tri-tert-butyl phenol 2,6 di-tert-butyl-methylphenol. The device has higher efficiency and a slower rate of degradation than devices lacking the hindered phenolic additive.

Claims

1. An electroluminescent device comprising:

a hole injection electrode;

an electron injection electrode; and

an electroluminescent layer comprising an organic polymer between said hole and electron injection electrodes, said electroluminescent layer further comprising a hindered phenolic additive in a concentration greater than 4% by weight, wherein said hindered phenolic additive is chosen from the group consisting of 2,6 di-tert-butyl-methylphenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, or 2,4,6 tri-butyl phenol.

2. The electroluminescent device of claim 1 wherein said electroluminescent layer comprises Poly (2,5-bis (5,6-dihydrocholestanoxy)-1,4-phenylene vinylene) or poly (2-methoxy-5-(2-'"'"'ethyl-hexoxy)-1,4-phenylene vinylene).

3. The electroluminescent device of claim 1 further comprising an electron transport layer between said electron injection electrode and said electroluminescent layer.

4. The electroluminescent device of claim 1 further comprising a hole transport layer between said hole injection electrode and said electroluminescent layer.

5. An electroluminescent material comprising Poly(2,5-bis(5,6-dihydrocholestanoxy)-1,4-phenylene vinylene), and poly(2-methoxy- 5-(2-'"'"'ethyl-hexoxy)-1,4-phenylene vinylene) in combination with a hindered phenolic additive, wherein said hindered phenolic additive is chosen from the group consisting of 2,6 di-tert-butylmethylphenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, or 2,4,6 tri-tert-butyl phenol.