Polymer Solar Cells Processed Using Anisole as a Relatively Nontoxic Solvent

In this study, a relatively nontoxic single solvent, anisole, was successfully used to process polymer solar cells. Blends cast with anisole showed higher polymer aggregation due to lower solubility. Polymer aggregation led to isolated regions that can trap charges in the polymer phase in anisole-based cells, supported by photo-charge extraction by the linearly increasing voltage (photo-CELIV) technique. However, polymer aggregation resulted in lower bimolecular recombination due to a decreased amount of polymer-PCBM interface as seen in transient photocurrent/photovoltage measurements. The higher charge trapping was compensated by the lower bimolecular recombination and therefore cells fabricated with anisole solvent delivered comparable photovoltaic performance to reference to cells processed with chlorobenzene (CB). Overall anisole was proved to be a friendly solvent to process organic photovoltaics thereby decreasing the risk to human health for large scale production.