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

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.