摘要： As-cast polymer solar cells without any additive and pre- or post-treatment principally are of high compatibility with mass production technologies, whose efficiencies are typically promoted by new donor and acceptor materials. In this work, a binary solvent approach using chloroform (CF) of low boiling point as good solvent for both polymer donor PTQ10 and non-fullerene acceptor IT-4Cl and mesitylene (MES) of relatively high boiling point as a semi-orthogonal co-solvent due to weaker solubility to the acceptor is explored. Due to the selective orthogonality of MES to the IT-4Cl acceptor, an optimized morphology has been realized for the as-cast device based on the PTQ10:IT-4Cl blend, which leads to a simultaneous improvement in the open-circuit voltage, short-circuit current, and fill factor, finally achieving a high as-cast efficiency of over 13%. Furthermore, the as-cast devices fabricated with the binary solvent can exhibit good air stability and great accessibility in large area cells. Our findings provide an alternative guideline for the optimization of the as-cast polymer solar cells.