Multi‐component Copolymerized Donors enable Frozen Nano‐morphology and Superior Ductility for Efficient Binary Organic Solar Cells

Abstract

Multi‐component copolymerized donors (MCDs) have gained significant interest and have been rapidly developed in flexible organic solar cells (f‐OSCs) in recent years. However, ensuring the power conversion efficiency (PCE) of f‐OSCs while retaining ideal mechanical properties remains an enormous challenge. The fracture strain (FS) value of typical high‐efficiency blend films is generally less than 8%, which is far from the application standards of wearable photovoltaic devices. Therefore, we developed a series of novel MCDs after meticulous molecular design. Among them, the consistent MCD backbone and end‐capped functional group formed a highly conjugated molecular plane, and the solubilization and mechanical properties were effectively optimized by modifying the proportion of solubilized alkyl chains. Consequently, due to the formation of entangled structures with a frozen blend film morphology considerably improved the high ductility of the active layer, P10.8/P20.2‐TCl exhibited efficient PCE in rigid (18.53%) and flexible (17.03%) OSCs, along with excellent FS values (16.59%) in pristine films, meanwhile, the outstanding FS values of 25.18% and 12.3% were achieved by P10.6/P20.4‐TCl ‐based pristine and blend films, respectively, which were one of the highest records achieved by end‐capped MCD‐based binary OSCs, demonstrating promising application to synchronize the realization of high‐efficiency and mechanically ductile flexible OSCs.