Thermodynamic and Kinetic Regulation of Acceptor Layer for Efficient Ambient‐Air‐Blade‐Coated Flexible Organic Photovoltaic Modules

ABSTRACT Scalable fabrication under ambient conditions is essential for scale‐up organic solar cells (OSCs), yet confronting the challenge of rational morphology regulation in the blade‐coated active layer. In this work, we develop BO‐4I as a nucleating agent to address the undesirable aggregation behavior of blade‐coated L8‐BO acceptor film. The relatively weak backbone π‐stacking while strong alkyl‐chain packing of BO‐4I, effectively lower the nucleation barrier and moderate the aggregation kinetics of L8‐BO, extending the reorganization window for ordered molecular packing. As a result, the collaborative regulation of BO‐4I heterogeneous nucleating agent and air‐knife treatment optimizes the crystallization and suppresses the disordered alkyl‐chain entanglement of L8‐BO, enabling desirable morphology in the blade‐coated D18/L8‐BO:BO‐4I film under ambient conditions in air. Consequently, the collaborative treatment of BO‐4I agent and air‐knife for the D18/L8‐BO‐based device significantly elevates the power‐conversion efficiency (PCE) from 9.88% to 19.41%, which is the highest value reported for the OSCs fabricated under ambient conditions in air. Particularly, such strategy enables a notable PCE of 14.75% in the D18/L8‐BO:BO‐4I‐based flexible module with an active area of 11.9 cm 2 , demonstrating its practical application for scale‐up flexible OSCs.