Diketopyrrolopyrrole-based polymer with a semi-fluorinated side chain for high-performance organic thin-film transistors

A diketopyrrolopyrrole ( DPP ) unit with a semi-fluorinated side chain was copolymerized with bithiophenyl ( BT ) to afford a novel donor-acceptor (D-A) conjugated polymer PFDPP-BT ( FDPP refers to the semi-fluorinated DPP unit). The non-fluorinated polymer PDPP-BT was synthesized as the reference polymer to investigate the effect of fluorination of side chains on the morphology of thin films and charge-carrier mobility. Organic thin-film transistors based on these two polymers showed decent device performance. Interestingly, the semiconductor polymer PFDPP-BT exhibited hole mobility about 3 times higher than that of the related PDPP-BT . Atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements demonstrated that the semi-fluorinated side chains had a great effect on the thin film morphology and crystallinity, which led to enhancement in device performance. A semi-fluorinated DPP based polymer showed hole mobility about 3 times higher than did its non-fluorinated analogue.