Breaking Morphology Limits: The Rise of Volatile Solid Additives in Organic Photovoltaics

The nanoscale morphology of the active layer is crucial in determining exciton generation, dissociation, and charge transport. In this regard, the solid additive strategy has surfaced as an effective approach for fine-tuning the morphology of the active layer during the film process. Notably, the incorporation of volatile solid additives (VSAs) has achieved significant enhancements with device efficiency approaching 21% for state-of-the-art organic solar cells. Here, this review categorizes recently reported VSAs into three distinct structural types including benzene, thiophene, and other types. We systematically explored their structure–function relationships and working mechanisms, aiming to gain deeper insights into the influence of VSAs on the morphology of the active layer and overall performance of the devices. Furthermore, this review addresses current challenges and future perspectives in VSA design with the intention of inspiring further progress in the field of organic photovoltaics.