The effect of additives on the morphology of organic solar cells: A brief review

Bulk heterojunction (BHJ) organic solar cells (OSCs) have achieved rapid development in the past decades, and their power conversion efficiency (PCE) has been improved to nearly 20%. The improvement of PCE is often inseparable from the morphology optimization of the active layer. Using different types of additives in the preparation of active layer is one of the most common strategies to optimize the morphology of active layer. In recent years, the application of additives in OSCs has become a hot research direction in the field of OSCs, but there are still great challenges in the in-depth understanding of the action mechanism of additives. Starting from the importance of morphology regulation for performance improvement of OSCs, this review summarizes the application research progress of additives (including solvent additives and solid additives) in OSCs and the regulation mechanism of active layer morphology. The current problems in the development of efficient additives were also discussed, which can provide guidance for the future development of additives in OSCs.