A universal processing additive for high-performance polymer solar cells

To optimize the performance of polymer solar cells, various techniques have been developed and reported from various research fields. The introduction of processing additives in the polymer : PCBM bulk-heterojunction solution is one of the efficient strategies used to improve the cell performance. Although numerous solvents have been presented as processing additives, an appropriate processing additive is always different for each polymer solar cell. In this manuscript, we demonstrate that diphenyl ether (DPE) works as a widely beneficial processing additive, which provides high-performance polymer solar cells from all types of photovoltaic polymers. DPE acts like a theta solvent to photovoltaic polymers, helps to form ideal bulk-heterojunction film morphologies and suppresses bimolecular charge recombination. This study suggests an efficient way to optimize the performance of polymer solar cells using DPE regardless of the photovoltaic polymers used.