Dithienobenzothiadiazole-Based Donor-Acceptor Polymer: Synthesis and Characterization for Organic Field-Effect Transistor

Abstract

Conjugated polymers with coplanar conformation backbones can form a closer π-π stacking self-assembly in solid films, producing high charge-carrier mobility in organic field-effect transistors (OFETs). In this work, a new donor-acceptor (D-A) copolymer (PDTFBT-TVT) including (E)-2-(2-(thiophen-2-yl)vinyl)thiophene and dithienobenzothiadiazole conjugated units is synthesized via Stille copolymerization. It is found that PDTFBT-TVT has a good planar backbone structure with an optical band gap of 1.89 eV. Spun-cast film contains preferentially edge-on orientated polymer chains with respect to a polymer-treated SiO2 dielectric, yielding a hole mobility (μh) of 0.06 cm2 V-1 s-1 in OFET. Thermal annealing enhanced the π-conjugated ordering and orientation of PDTFBT-TVT chains in the spun-cast films. The annealed film-based OFETs show a considerable enhancement in μh up to 0.22 cm2 V-1 s-1, as well as high on/off current ratio of > 106.