All‐Green Solvent and Additive Combination Enables Efficient Nonfullerene Organic Solar Cells via Sequential Deposition Strategy

The performance of organic solar cells mainly depends on the morphology of the active layer. Traditional solution‐processed active layers have poor performance due to the random distribution of donor and acceptor materials during solution processing. In addition, halogenated solvents and additives widely used in traditional fabrication processes will have a huge impact on human health and the environment. Herein, an all‐green solvent and additive combination strategy is proposed to assist the morphology control of the active layer with sequential deposition (SD) technique. Ultimately, with adopting benzyl viologen (BV) additive as well as ethyl alcohol treatment, PM6:Y6‐2BrO‐based devices yield a power conversion efficiency of 14.3%, higher than those of the control device (13.24%) and the device solely with BV additives (13.62%). The result demonstrates the feasibility of SD technique to finely control the morphology of active layer in future all‐green industrial production.