Multicolor oligothiophene-based light-emitting diodes

We demonstrate wide tunability, from green to near infrared, of the electro luminescence emission of substituted oligothiophene compounds. The compound s are characterized by high chemical stability, electron affinities up to 3 .1 eV and photoluminescence efficiencies up to 70%. These characteristics m ake these materials excellent candidates for application in light-emitting diodes. We obtain low turn-on voltage devices with electroluminescence effi ciency up to 0.2%, more than one order of magnitude larger than the values reported for unsubstituted oligothiophene compounds. (C) 2001 American Inst itute of Physics.