A liquid-crystalline semiconducting polymer based on thienylene–vinylene–thienylene: Enhanced hole mobilities by mesomorphic molecular ordering and thermoplastic shape-deformable characteristics

Abstract

Liquid-crystalline (LC) π-conjugated polymers are an emerging class of semiconducting materials owing to their promising performance in organic field-effect transistors (OFETs). Little is known, however, about the relationship between LC nature and charge carrier mobility. In this paper, we focus on a thiophene-based p-type semiconducting polymer, PC12TV12T, containing thienylene–vinylene–thienylene (TVT) units, and report a systematic investigation of its thermotropic LC properties, self-organized structures in bulk and thin films, as well as charge transport properties in OFETs. We found that thermal annealing at LC temperatures (99–170 °C) strongly enhanced OFET performance, leading to field-effect hole mobilities as high as 0.37 cm2 V−1 s−1, comparable to that of amorphous silicon. By virtue of its thermoplasticity, the TVT-based polymer can also be processed into fine semiconducting microfibers, which can even function as a p-type active channel for charge transport. This bottom-up technology utilizing the LC nature enables cost-effective and energy-efficient manufacture of optoelectronic devices. A π-conjugated polymer based on thienylene–vinylene–thienylene (TVT) units can form a thermotropic liquid-crystalline (LC) mesophase over a wide temperature range. Thermal annealing at LC temperatures strongly enhanced hole mobilities in organic field-effect transistors (OFETs) owing to improved molecular ordering. Because of its thermoplasticity, the TVT-based π-conjugated polymer can also be processed into semiconducting fine microfibers and serve as a charge transport pathway in microfiber OFETs.