Manipulating Aggregation Kinetics toward Efficient All‐Printed Organic Solar Cells

Abstract The power conversion efficiencies (PCEs) of all‐printed organic solar cells (OSCs) remain inferior to those of spin‐coated devices, primarily due to morphological variations within the bulk heterojunction processed via diverse coating/printing techniques. Herein, cyclohexyl is introduced as outer side chains to formulate a non‐fullerene acceptor, BTP‐Cy, aimed at modulating the molecular aggregation in solution and subsequent film formation kinetics during printing. Investigations demonstrate that BTP‐Cy molecule with cyclohexyl side chains exhibits enhanced intermolecular π‐π stacking, optimal solution aggregation size, and favorable phase separation. Consequently, PB3:FTCC‐Br:BTP‐Cy‐based OSCs achieve remarkable PCEs of 20.2% and 19.5% via spin‐coating and blade‐coating, respectively. Furthermore, a 23.6 cm² module exhibits a remarkable efficiency of 16.7%. This study offers a fresh perspective on tailoring the film formation kinetics of photoactive materials during printing through molecular design, paving a novel path to enhance the efficiency of all‐printed OSCs.