A new green solvent, cyclopentyl methyl ether (CPME), has been applied to replace toxic chlorinated solvents in the production of efficient molecular photovoltaics. We employed a conjugated small molecule (SMPV1) as donor and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) as the acceptor in solar cell devices. Using CPME-only as the host solvent, power conversion efficiency (PCE) of 3.13% was achieved. The low PCE came from the low PC₆₁BM solubility in this green solvent. Accordingly, we introduced toluene (Tol) in different amounts as a co-solvent for CPME. The greater solubility of PC₆₁BM in these mixtures led to significant improvements in the short-circuit current density and fill factor of the device, achieving a PCE of 7% after processing in the optimized green solvent mixture of CPME:Tol. Thermal annealing (TA) of the active layers processed from the optimized green solvent mixture enhanced the PCE to 8.10%. This efficiency is the highest reported for a molecular solar cell processed from a green solvent mixture to date. Large-scale devices fabricated this way, having areas of 1 and 5.5 cm², exhibited PCEs of 6.20 and 3.73%, respectively. The morphological changes that occurred when applying the co-solvent and TA played key roles in achieving such high PCEs. This work paves the way toward organic photovoltaics scaling up using green solvents.