A Terpolymer Acceptor Enabling All‐Polymer Solar Cells with a Broad Donor:Acceptor Composition Tolerance and Enhanced Stability

Achieving a broad donor:acceptor (D:A) composition tolerance in efficient organic solar cells (OSCs) is important for printing large‐area solar cell modules. Herein, all‐polymer solar cells (all‐PSCs) based on new terpolymer acceptors and a well‐known polymer donor PTB7‐Th are fabricated to explore the effect of D:A ratio on morphology and photovoltaic performances. The all‐PSCs show a promising power conversion efficiency (PCE) of 7.23% with an optimum D:A ratio of 1:2 and retain over 40% of its optimal PCE with ultrabroad D:A composition tolerance from 1:30 to 10:1. In addition, the all‐PSCs can maintain 90% of its original PCE after 400 h of storage despite such broad range of D:A ratio, which is much better than those of other types of OSCs and even better than the benchmark all‐polymer system with N2200 as the acceptor under the same condition. The results show the superiority of the all‐PSCs in terms of D:A ratio tolerance and performance stability, which should be conducive to practical applications of all‐PSCs. A new PBTI2(30HD)‐FT terpolymer acceptor enables all‐polymer solar cells (all‐PSCs) with an ultrabroad donor:acceptor (D:A) ratio tolerance from 1:30 to 10:1 and better stability than other types of organic solar cells. PBTI2(30HD)‐FT can lead to well‐maintained interpenetrating network even at very low loading in blend films, yielding decent photovoltaic performance.