Low-Cost, High-Efficiency Organic Solar Cells Based on Ecofriendly Processing Solvent

Developing organic photovoltaic materials at low-cost and processing with eco-friendly solvents are promising strategies to solve the critical issues of organic photovoltaic. Key hurdles for commercialization are synthetic complexity of the donor and the prevalent casting from hazardous solvents. Herein, by choosing PTQ10 as a low-complexity donor and optimizing PTQ10:BTP-eC9 and PTQ10:Y6 devices cast from chloroform (CF) and o-xylene (XY), we demonstrate excellent performance with the eco-friendly solvent XY relative to the CF standard. We find the XY-processed devices exhibit a PCE of 16.53%, which is higher than the CF-processed OSCs (16.39%) and it is one of the highest values among PTQ10-based binary systems. Furthermore, we investigated the adaptability in fabricating large-area devices via the blade-coating method. By using CF and XY solvents in 1 cm2 devices, a PCE of 14.94% for XY-solvent and 12.86% for CF-solvent was achieved. We further studied the aggregation kinetics by time-resolved in situ UV-Vis absorbance measurements to understand differences in bulk heterojunction formation. We observe an overall longer time with XY over CF that improves the reproducibility with XY. We successfully transitioned from toxic solvents to eco-friendly alternatives without sacrificing efficiency, combined with a low-cost donor polymer, advancing future practical and commercial applications.