Regulation of Polymer Configurations Enables Green Solvent‐Processed Large‐Area Binary All‐Polymer Solar Cells With Breakthrough Performance and High Efficiency Stretchability Factor

Abstract With the great potential of the all‐polymer solar cells for large‐area wearable devices, both large‐area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX‐A and PYTX‐B (X = Cl or H) are developed. The configuration difference caused by the replacement of non‐conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film‐forming of the active materials and the technically slow film‐forming of the blade‐coating process, the toluene‐processed large‐area (1.21 cm²) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl‐A and PM6:PYTCl‐B yield significantly higher ESF than PM6:PY‐IT. Further blending with non‐conjugated polymer donor PM6‐A, the best ESF of 3.12% is achieved for PM6‐A:PYTCl‐A, which is among the highest comprehensive performances.