New environmentally friendly polyazomethines with thiophene rings for polymer solar cells

We synthesized two new, air-stable and environmentally friendly polyazomethines and characterized their photovoltaic and electrochemical impedance spectroscopic properties. Two polyazomethines with one (25Th-DMB) or three (2252Th-DMB) thiophene rings were synthesized and tested as donors in the active layer in solar cells. The investigated polymer solar cells contained different amounts of PCBM and PC71BM. The bulk heterojunction polymer solar cells were fabricated and studied, considering the architecture of the devices (i.e., LiF, TiO2, and TiO2:Ag) and the fabrication conditions (i.e., air, inert gas, and annealing). The highest power conversion efficiency, which was equal to 0.52% under simulated 100 mW/cm2 AM 1.5G irradiation, was determined for the device using polyazomethine with three thiophene rings and PC71BM created in air with the ITO/PEDOT:PSS (100 cP)/2252Th-DMB:PC71BM (1:2)/Al architecture. In addition, the power conversion efficiency was strongly dependent on the viscosity of the PEDOT:PSS used.