Amelioration of opto – electronic response of thiophene - Imidazo[2,1-b][1,3,4]thiadiazole based organic semiconductors

Two new donor-acceptor (D – A) type organic semiconductors V-1 and V-2 containing thiophene as the donor unit were designed and synthesized following Knoevenagel condensation reaction. The structures of the synthesized molecules were characterized by mass spectroscopy and ¹H NMR spectroscopy. The photophysical properties were investigated by UV-vis spectroscopy and fluorescence spectroscopy. The electrochemical properties were studied by cyclic voltammetry. The density functions theory (DFT) studies were performed to examine the frontier molecular orbital energy states. Both electrochemical analysis and DFT studies revealed that the HOMO of V-2 is shifted to higher energy compared to that of V-1 due to the stronger electron donating ability of methoxy group in V-2 compared to that of methyl group in V-1. The optical and electrochemical results revealed that the synthesized organic semiconductors are suitable donor materials for bulk hetero - junction solar cells.