Efficient light emitting diodes from polyfluorene copolymer blends

Cirpan A., Ding L., Karasz F.

SYNTHETIC METALS, vol.150, no.2, pp.195-198, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 150 Issue: 2
  • Publication Date: 2005
  • Doi Number: 10.1016/j.synthmet.2005.02.003
  • Journal Name: SYNTHETIC METALS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.195-198
  • Middle East Technical University Affiliated: No

Abstract

Highly efficient light emitting diodes were obtained by blending blue-emitting poly [(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(N,N'-diphenyl)-N,N-di(p-butyl-oxyphenyl)-1 ,4-diaminobenzene] (1) with green-emitting poly [(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (II). Only green emission was obtained from the films of polymer blends and from corresponding double-layer LEDs, indicating an almost complete Forster energy transfer from I to II. These devices show enhanced external quantum efficiency, higher brightness and lowor turn on voltages. Luminance and efficiency of 2.6 x 10(4) cd/m(2) and 2.55%, respectively, were obtained. (c) 2005 Elsevier B.V. All rights reserved.