Incorporation of Thieno[3,2- b ]pyrrole into Diketopyrrolopyrrole-Based Copolymers for Efficient Organic Field Effect Transistors.

Recent advancements in organic field effect transistors have switched chemists' focus from synthesizing libraries of organic semiconductors to a more targeted approach where chemical alterations are performed on known semiconductors to further improve electronic properties. Among successful semiconducting polymer candidates, copolymers based on diketopyrrolopyrrole-and thieno[3,2- b ]thiophene [ P(DPP-TT) ] have been subjected to modifications on the diketopyrrolopyrrole unit by using flanking groups and side chain engineering. Thieno[3,2- b ]thiophene moiety, however, has seen minimal modifications due to the limited number of modifying sites. Isoelectronic thieno[3,2- b ]pyrrole could serve as an alternative since it is easily tunable via N-alkylation reactions. Therefore, for the first time, we report the replacement of the thieno[3,2- b ]thiophene unit of P(DPP-TT) with thieno[3,2- b ]pyrrole unit and its performance in p-channel field effect transistors. The copolymer exhibits linear characteristics to achieve a relatively high average hole mobility of 0.12 cm 2 V -1 s -1 in bottom-gate/top-contact field effect transistors with threshold voltages as low as 0 V. These preliminary results highlight the potential of this thieno[3,2- b ]pyrrole monomer for utilization in organic field effect transistors.