Chlorinated 2,1,3-Benzothiadiazole-Based Polymers for Organic Field-Effect Transistors

The vital role of introducing chlorine (Cl) atoms onto conjugated polymers, which affects their semiconducting properties, is not yet well understood. A series of donor–acceptor polymers based on dichlorinated-2,1,3-benzothiadiazole (2ClBT) and four different donor moieties with various conjugation lengths (thiophene (T), thieno[3,2-b]thiophene (TT), 2,2′-bithiophene (DT), and (E)-2-(2-(thiophen-2-yl)vinyl)thiophene (TVT)) were synthesized and used in organic field-effect transistors (OFETs). The structure–property relationship associated with the 2ClBT-based polymers was thoroughly investigated via a range of techniques, and it was found that a change in the conjugation length of the main backbone could alter energy levels, morphology, and optoelectronic properties, which had a significant effect on the charge transport property. P2ClBT-TVT exhibited superior qualities relative to the other samples with respect to the degree of uniform film-forming ability and molecular organization and charge carrier tr...