A theoretical investigation of 4,7-di(furan-2-yl)benzo[c][1,2,5]selenadiazole-based donor–acceptor type conjugated polymer

Quantum chemical calculations are performed using density functional theory (DFT) to investigate the HOMO–LUMO energy gap of the 4,7-di(furan-2-yl)benzo[c][1,2,5]selenadiazole-based (FSeF) donor–acceptor type conjugated polymer which ascertains the optoelectronic properties and plays a crucial role, especially in polymeric solar cell applications. In this paper, the most stable conformers of the FSeF monomer and its corresponding oligomers are investigated at the B3LYP/Def2TZV and B3LYP/LANL2DZ levels of theory, and their molecular structures are revealed. The band gap of the polymer is determined by linear-fitting and extrapolation of the DFT data. This gap is found to be 1.44 eV and 1.45 eV by the B3LYP/Def2TZV, and B3LYP/LANL2DZ with PCM calculations, respectively. Our theoretical findings related to the band gap of the FSeF polymer (PFSeF) are in good agreement with other experimental studies in the literature and, hence, the theoretical methods used in this study are promising for the design of similar donor–acceptor type novel conjugated polymers.