Effect of different solvents on the performance of ternary polymer solar cells based on PTB7 : PC₇₁BM : F8BT

The effect of different solvents on the active layer morphologies and PTB7 : PC₇₁BM : F8BT ternary polymer solar cells (PSCs) performance were systemically investigated by applying various solvents, including chlorobenzene (CB), 1, 4-dichlorobenze (DCB), p-xylene (XY), and mixtures of chlorobenzene and 1, 8-diiodooctane (DIO). The optimized photovoltaic performance increased 5% compared with the reference binary PTB7 : PC₇₁BM (1 : 1.5) PSCs. The performance improvement was mainly attributed to the improved quality of donor-acceptor interfaces cast from a proper solvent, as well as the fuller coverage of the solar radiation spectrum provided by the blend film. By analyzing the variation of PSCs performance and the morphology of active layers, we found that the proper solvent and the additive were playing an important role on better charge transfer efficiency and more balanced charge separation. (paper)