EFFICIENT ELECTROLUMINESCENCE IN REGIOREGULAR POLYALKYLTHIOPHENE LIGHT-EMITTING-DIODES

The regioregular poly(3-alkylthiophenes) (PATs) were used as active ma terials in polymer-based light-emitting diodes (LEDs). Bright green el ectroluminescence (EL), peaked at 540 nm, was observed with quantum ef ficiency of about 0.5% photons/electron. Polymers with different lengt hs of alkyl side groups were used. This fact however did not change EL yield and peak position. Additionally, optical absorption and photolu minescence spectra are presented. Finally, the presented data are refe rred to the recently published theoretical results on the photoexcited species in oligothiophenes. (C) 1998 Elsevier Science S.A. All rights reserved.