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.