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 cm² 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.