Volatile Additives Engineering: A Trustworthy Morphology Control Strategy in Non-Fullerene Organic Solar Cells.

Over the past few years, the efficiency of organic solar cells (OSCs) has significantly increased from about 15% to 21%. The morphology of the photoactive layer plays a critical role in performance improvement of OSCs. Therefore, numerous methods have been developed to optimize the morphology of the photoactive layer and unlock the full potential of the devices. Among them, volatile solid and solvent additives have attracted considerable attention due to their robust enhancement of efficiency and stability, coupled with a simple operational process. Here, the classification and development history of the volatile solid and solvent additives are comprehensively summarized, and the underlying mechanisms of morphology optimization are discussed. Additionally, a summary of volatile additive-induced improvements in interfacial layer performance is provided. Finally, the challenges and prospects for volatile additives are presented.