Amorphous Dithenylcyclopentadienone-Carbazole copolymer for Organic Thin-Film Transistors*

We developed a new high performance amorphous donor-acceptor conjugated copolymer consisting dithienylcylclopentadienone subunit as an electron acceptor and carbazole derivative as an electron donor. X-ray diffraction analysis shows no scattering patterns, indicating a disordered amorphous solid is formed. A high on/off current ratio of approximately 10$^{6}$ and a high field effect mobility of 2.24\times$10$^{-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.