The backbone rigidity and its influence on the morphology and charge mobility of FBT based conjugated polymers

A series of three PVTh4FBT polymers containing different alkyl side chain placement was synthesized. The thermochromic behaviors and DFT calculations indicated that the backbone coplanarity and rigidity of the PVTh4FBT polymers can be effectively modulated by adjusting the side chain position and density. Higher ordered and better oriented edge-on lamellar packing was formed by P1, which possesses the most rigid backbone among the three polymers and pre-aggregates in the solution. P1 also delivered the highest hole mobility (0.26 cm(2) V-1 s(-1)) among the three analogues because its thin-film morphology is in favor of charge transport.