Fluorodiphenylethene-Containing Donor–Acceptor Conjugated Copolymers with Noncovalent Conformational Locks for Efficient Polymer Field-Effect Transistors

Abstract

The diphenylethene moiety is a versatile building block that offers several chemically functionalizable sites, allowing easy modulation of electronic properties of the resulting polymers and providing numerous opportunities for discovering related structure–property relationships. In this study, we report a series of difluorodiphenylethene-based copolymers with noncovalent conformational locks for applications in polymer field-effect transistors. Different fluorination positions lead to different type of intra- and intermolecular interactions, backbone conformations, and eventually different device performances. 2,2′-Difluorodiphenylethene-based copolymers P2DFPE-n containing F···H–C conformation locks exhibit obviously enhanced hole mobilities of 1.3–1.5 cm2 V–1 s–1, whereas 3,3′-difluorodiphenylethene-based copolymers P3DFPE-n containing F···H–C and F···S conformation locks show lower mobilities of 0.2–0.4 cm2 V–1 s–1. AFM and 2D-GRXD investigations indicate that P2DFPE-n takes predominantly edge-on orientation packing mode, forming crystalline and highly ordered thin films with small π–π stacking distances of 3.59–3.68 Å. However, P3DFPE-n adopts random close molecular packing mode in solid states.