Rational Regulation of the Molecular Aggregation Enables A Facile Blade‐Coating Process of Large‐area All‐Polymer Solar Cells with Record Efficiency

Abstract Developing robust materials is very critical and faces a big challenge for high‐performance large‐area all‐polymer solar cells (all‐PSCs) by printing methods. Herein, the authors combine the advantages of the terpolymerization strategy with the non‐conjugated backbone strategy to regulate the molecular aggregation rationally during the film‐forming printing process, facilitating a facile printing process for large‐area all‐PSCs. A series of terpolymer acceptors PYSe‐Clx (x = 0, 10, 20, and 30) is also developed, which can effectively fine‐tune the morphology and photoelectric properties of the active layer. The PBDB‐T: PYSe‐Cl20‐based all‐PSC delivers a significantly improved power cconversion efficiency (PCE) than the one with PBDB‐T: PYSe (14.21% vs 12.45%). By addition of a small amount of non‐conjugated polymer acceptor PTClo‐Y, the ternary all‐PSC reaches a PCE of 15.26%. More importantly, the regulation of molecular aggregation enables a facile blade‐coating process of the large‐area device. A record PCE of 13.81% for large‐area devices (1.21 cm²) is obtained, which is the highest value for large‐area all‐PSCs fabricated by blade‐coating. The environmentally friendly solvent processed large‐area device also obtains an excellent performance of 13.21%. This work provides a simple and effective molecular design strategy of robust materials for high‐performance large‐area all‐PSCs by a printing process.