Recent Progress of Solid Additives in Organic Solar Cells.

Morphology is a critical determinant of the photovoltaic performance of organic solar cells (OSCs), as it governs charge generation, separation, and transport by regulating nanoscale phase separation and molecular packing within the active layer. Among the various strategies developed to control morphology, solid additives (SAs) have emerged as a particularly promising approach. Offering advantages such as low cost and ease of incorporation, SAs enable precise tuning of active layer morphology without the need for complex synthetic modification. By promotion of favorable nanoscale phase separation, SAs can facilitate the formation of well-organized domains that enhance charge transport pathways while reducing charge recombination losses. Recent advances have underscored the significant potential of SA engineering in advancing OSCs toward large-scale commercial deployment. This review provides a comprehensive summary of recent progress in SA development with a particular emphasis on their roles in regulating film formation dynamics and optimizing morphologies. Finally, we highlight the remaining challenges and propose future research directions to further exploit SA engineering in the realization of high-efficiency, stable organic photovoltaic devices.