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Four different kinds of photovoltaic polymers were synthesized by controlling the intrachain noncovalent coulomb interactions through the incorporation of alkoxy- or alkylthio-substituted phenylene, 4,7-di(furan-2-yl)benzothiadiazole, and 4,7-di(thiophen-2-yl)benzothiadiazole as a building block. Fine modulation of the interplay of dipole–dipole, H-bond, and chalcogen–chalcogen interactions (O···S, O···H, S···S, S···F, etc.) along the polymeric backbone influenced the chain planarity, interchain organization, film morphology, and electrical and photovoltaic properties significantly. By replacing the alkoxy substituents with alkylthio groups, the torsional angle increased (136–168°) due to the absence of an O···S attractive coulomb interaction (and/or increased S···S steric hindrance), enhancing the amorphous nature with hindered interchain packing. The alkoxy-substituted polymers exhibited nanofibrillar structures, showing strong interlamellar scattering peaks up to (300) with tight face-on π–π stacking i...

We report a series of benzotriazole-based semicrystalline π-conjugated polymers with noncovalent conformational locks for applications in polymer field-effect transistors. The benzotriazole moiety is a versatile electron-deficient building block that offers two chemically functionalizable sites, 2(N) and 5, 6(C) positions, allowing easy modulation of the solution processability and electronic structures of the resulting polymers. Fluorine or alkoxy substituents were introduced to the benzotriazole unit to enhance the molecular ordering through intra- and intermolecular F···S, F···H–C, C–F···πF, or S···O attractive interactions. The fluorinated polymer (PTBTz-F) showed remarkably enhanced hole mobility (μh = 1.9 cm2/(V·s), on/off ratio = 8 × 107) upon thermal annealing at 305 °C, compared to the unsubstituted one (PTBTz) (μh = 7.0 × 10–3 cm2/(V·s), on/off ratio = 3 × 106). Alkoxy unit substitution (PTBTz-OR) also improved the carrier mobility up to 0.019 cm2/(V·s) with an on/off ratio of 4 × 105. Fluorine ...