Synthesis and characterisation of a new series of 2,6-linked-anthracene–benzothiadiazole based polymers for organic solar cells applications

Abstract

A series of medium band gap alternating donor-acceptor conjugated polymers based on 2,6-linked anthracene flanked by thienyl donor units and benzothiadiazole acceptor units (BT) are prepared via direct arylation polymerization reactions. The prepared polymers show multiple absorption bands in both solutions and thin films with optical band gaps in the range of 1.75–1.85 eV. Polymers with alkylthienylethynyl substituents on the 9,10-positions of anthracene repeated units show broader absorption spectra compared to a polymer with alkynyl substituents. Photovoltaic studies of poly [9,10-bis [2-ethynyl-5-dodcylthiophene]-anthracene-2,6-diyl-alt-4,7-di(thiophene-2-yl)benzo [c] (Gopalakrishnan et al., 2022; Gokulnath et al., 2021; Bian et al., 2012) [1,2,5]thiadiazole] PATA(D)TBT in this series, blended with phenyl-C70-butyric acid methyl ester PC71BM shows a power conversion efficiency PCE of 0.76% and an open circuit voltage Voc of 0.54 V.