Central Core Substitutions and Film-formation Process Optimization Enable Approaching 19% Efficiency All-Polymer Solar Cells.

Molecular interactions and film-formation processes greatly impact the blend film morphology and device performances of all-polymer solar cells (all-PSCs). The molecular structure, such as the central cores of polymer acceptors, would significantly influence this process. In this article, we adjusted the central core substitutions of polymer acceptors and synthesized three quinoxaline (Qx)-fused-core-based materials, PQx1, PQx2, and PQx3. The molecular aggregation ability and intermolecular interaction were systematically regulated, which subsequently influenced the film-formation process and determined the resulting blend film morphology. As a result, PQx3, with favorable aggregation ability and moderate interaction with polymer donor PM6, achieved efficient all-PSCs with a high PCE of 17.60%, which could be further improved to 18.06% after collaborative use of thermal annealing, solvent annealing, and interface engineering strategies. This impressive PCE is one of the highest value for binary all-PSCs based on the classical polymer donor PM6. PYF-T-o was also involved in promoting light utilization, and the resulting ternary device showed an impressive PCE of 18.82%. In addition, PM6:PQx3-based devices exhibited high film-thickness tolerance, superior stability, and considerable potential for large-scale devices (16.23% in 1 cm 2 device). These results highlighted the importance of structure optimization of polymer acceptors and film-formation process control for obtaining efficient and stable all-PSCs. This article is protected by copyright. All rights reserved.