Synthesis of bis(thiophen-2-yl)benzothiadiazole scaffold donor-acceptor polymers: studies of polymerization, electrical, optical, and photovoltaic properties

Facile and efficient synthesis of conjugated donor-acceptor polymers via direct C-H arylation polymerization has received significant interest in organic electronic applications. We report here a one-pot synthesis of a series of bis(thiophen-2-yl)benzothiadiazole-based donor-acceptor polymers P1-4 via direct C-H arylation polymerization in excellent yield. Two donor moieties [3-hexylthiophene and 1,4-bis(dodecyloxy)benzene], and one acceptor unit 4,7-bis(thiophen-2-yl)benzo[c][1,2,5]thiadiazole were used for direct C-H arylation polymerization. The prowess of the methodology was applied to synthesis of polymer by adding one donor unit followed by a second donor unit after the due course. The resulting polymers are soluble and characterized. Optical and electrochemical properties were carried out by UV-Vis-NIR and cyclic voltammetry, respectively. A temperature-dependent absorption of the polymer films blended with PC₇₁BM was studied for photovoltaic application. Devices were fabricated by solution-processable deposition of active layer and a PCE of 3.82% was achieved.