Modulating the Growth of Nonfullerene Acceptors Toward Efficient and Stable Organic Solar Cells Processed by High‐Boiling‐Point Solvents

Abstract High‐boiling‐point solvents are considered to be decent solvents for the preparation of large‐area organic solar cells (OSCs) because of their wide processing window. However, the efficiency of OSCs processed by high‐boiling‐point solvents is still unsatisfactory. Herein, it is found that the agglomerate growth of nonfullerene acceptors into micrometer‐sized domains is the main reason for poor efficiency. A facile rapid molding process (RMP) scheme is proposed to solve this problem by adjusting the nucleation and growth behavior of acceptor molecules. RMP enables the blend films with interpenetrating networks and higher crystallinity, which is in favor of faster exciton separation and lower recombination losses. As a result, the power convention efficiency (PCE) is improved from 15.91% (reference) to 18.32% (RMP) for PL1:BTP‐eC9‐4F OSCs. To the best of the authors' knowledge, this is the champion efficiency of OSCs processed with high‐boiling‐point solvents. Meanwhile, RMP devices maintain 85% or 90% of the initial PCE after real day/night cycling in the air for over 2000 h or after continuous thermal aging at 85 °C in nitrogen for 500 h, respectively.