Efficient electroluminescence in regioregular polyalkylthiophene light-emitting diodes

The regioregular poly(3-alkylthiophenes) (PATs) were used as active materials in polymer-based light-emitting diodes (LEDs). Bright green electroluminescence (EL), peaked at 540 nm, was observed with quantum efficiency of about 0.5% photons/electron. Polymers with different lengths of alkyl side groups were used. This fact however did not change EL yield and peak position. Additionally, optical absorption and photoluminescence spectra are presented. Finally, the presented data are referred to the recently published theoretical results on the photoexcited species in oligothiophenes.