Amorphous dithenylcyclopentadienone-carbazole copolymer for organic thin-film transistors

Abstract

We developed a new high performance amorphous donor-acceptor conjugated copolymer consisting of a dithienylcylclopentadienone subunit as an electron acceptor and carbazole derivative as an electron donor. X-Ray diffraction analysis shows no scattering patterns, indicating that a disordered amorphous solid is formed. Atomic force microscopy (AFM) images show an amorphous surface mophology regardless of the annealing temperature. A high on/off current ratio of approximately 106 and high field effect mobility of 2.2 x 10(-2) cm(2) V(-1) s(-1) were obtained with stable output characteristics. The high performance of the amorphous copolymer is ascribed to the relatively low activation energy and low characteristic temperature obtained from a low temperature transport analysis, reflecting that localization of the charge carrier is not substantial in the film.