Synthesis and FET characterization of novel ambipolar and low‐bandgap naphthalene‐diimide‐based semiconducting polymers

Abstract

ABSTRACTA novel series of naphthalene‐diimide‐based semiconducting polymers (P1–P4) containing benzodithiophene or dithienopyrrole were successfully synthesized for ambipolar semiconducting materials showing near infrared absorptions. The incorporation of a 3‐hexylthiophene (3HT) spacer extended the intramolecular charge‐transfer (ICT) peak from λonset = 739 nm (P1) to 785 nm (P3). Moreover, about 250 nm red‐shift of the ICT peaks was observed in P2 and P4 compared to P1 and P3 due to the increased high‐lying HOMO energy levels. The grazing incidence X‐ray scattering of the P3 and P4 films proved the slightly improved crystalline order in the π−π stacking direction, indicating that the planar backbone is probably due to the introduced 3HT. The P1–P4‐based field‐effect transistor showed n‐type dominant ambipolar characteristics. The P2 and P4 showed higher electron mobilities up to 1.5 × 10−2 cm2 V−1 s−1 than P1 and P3, which might be influenced by the orientation of the polymer backbone and the intermolecular orbital overlap. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 359–367