Kinetics Manipulation Enabled by Solubility Control Toward 19% Organic Solar Cells via Compatible Air Coating

Blade coating is a promising tool for upscaling organic solar cells (OSCs). However, the performances of blade-coated OSCs still lag behind their spin-coated counterparts, limiting their competitive edge towards commercialization. One of the main reasons is that controlling the film aggregation kinetics and morphology becomes challenging during the transition from spin coating to blade coating, especially when using high boiling point solvents, which can result in excessive aggregation. Therefore, a deeper understanding and appraisal of film formation kinetics influenced by coating methods is crucial. In this work, it is demonstrated that ink solubility tuning by incorporating a twisted third component (BTP-4Cl) can induce rapid crystallization behavior and promote fine phase separation between the donor polymer (PM6) and the acceptor (BTP-eC9) in blade coating. As a result, a high power conversion efficiency (PCE) of 19.67% is obtained in OSCs (0.04 cm²), one of the state-of-the-art efficiencies among the reported blade-coated OSCs (19.76% for the spin-coated devices). In addition, it is found that the inhibited phase aggregation contributes to enhancing the light stability of the device. This strategy offered novel insights into the effectiveness of solubility-tuning approaches for achieving highly efficient and stable OSCs under open-air coating conditions.