Synthesis and Optoelectronic Characterizations of Conjugated Polymers Based on Diketopyrrolopyrrole and 2,2′‐(thieno[3,2‐b]thiophene‐2,5‐diyl)diacetonitrile Via Knoevenagel Condensation

Abstract Conjugated polymers have attracted extensive attention as semiconducting materials in wearable and flexible electronics. In this study, we utilize atom‐economical Knoevenagel reaction to construct two conjugated polymers, PTDPP‐CNTT and PFDPP‐CNTT , based on dialdehyde‐thiophene/furan‐flanked diketopyrrolopyrrole (DPP) and 2,2′‐(thieno[3,2‐ b ]thiophene‐2,5‐diyl)diacetonitrile (CNTT). The resulting polymers exhibited suitable highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) energy levels, small bandgaps, and broad UV–vis–NIR absorptions (≈400–1000 nm), endowing them with photothermal and balanced ambipolar semiconducting properties with hole and electron mobilities over 10 −3 cm 2 V −1 s −1 . Additionally, PTDPP‐CNTT ‐based organic field‐effect transistors (OFETs) devices show photo‐responsive characteristics at 808 and 980 nm in the hole transport channel with the photo‐responsivenesses of 9.0 × 10 −3 A/W and 0.4 A/W, respectively, suggesting potential application in organic NIR‐phototransistors.