Regioregular Asymmetric Diketopyrrolopyrrole Copolymers with Good Molecular Ordered Assembly Ability for High-performance Polymer Transistors

Introduction of asymmetric units into conjugated polymers is an important strategy to regulate the photophysical and electronic properties of polymers, as asymmetric units can not only regulate solubility and energy levels, but also molecular stacking and orientation, thus giving much higher optoelectronic properties. However, very few studies have been reported in this field. The semiconducting properties of conjugated polymers could be regulated through regioregularity adjustment. Here, we took the asymmetric thiophene/pyridine side group DPP as core and developed the regioregular monomer T-Py-DPP through three steps: alkyl chain introduction, tin monomer coupling and NBS double bromination. The T-Py-DPP monomer was polymerized into reg-PPyTDPP-2FBT with a head-to-head structure. The regioregularity of T-Py-DPP unit endowed reg-PPyTDPP-2FBT with backbone planarity, self-assembly orientation, network-like morphology and high crystallinity in films, thus the superior bipolar transport properties. The highest hole and electron mobilities of reg-PPyTDPP-2FBT were 0.93 and 0.57 cm(2)center dot V-1 center dot s(-1), respectively, with 40% improvement relative to the regiorandom polymer.