Modulating the Central Units of Polymerized Nonfused Electron Acceptors for All-Polymer Solar Cells

Polymerized small-molecule acceptors (PSMAs) based on nonfused-core structures have obtained much attention in the domain of all-polymer solar cells (all-PSCs) due to simplified synthetic complexity. In this work, two nonfused PSMAs, namely, P1 and P2, with similar molecular backbones but with the central units featuring two alkoxy side chains with varied substitution positions have been designed and synthesized. In P1, two alkyloxy side units locate at the two sides of the benzene core, while in P2, they locate on the same side. All-PSCs are fabricated by utilizing PBDB-T as the donor, followed by the investigation of their device performance. The P2 -based all-PSCs yield a power conversion efficiency of 9.33% with a robust short-circuit current ( J SC ) of 16.93 mA/cm 2 due to favorable active-layer morphology. Herein, it is demonstrated that optimizing the central unit is conducive to the development of high-performance polymer acceptors, which are essential for manufacturing low-cost and efficient all-PSCs.