High-performance binary all-polymer solar cells enabled by a Y-derivative pendant random-copolymerized polymer acceptor with a broad donor-acceptor matching tolerance

The fine-tuning of molecular aggregation and optimization of blend microstructures through effective molecular design strategies to simultaneously achieve high device efficiency and stability in all-polymer solar cells (all-PSCs) remain a significant challenge. This study presents a new design of random terpolymerization polymer acceptors (PAs) achieved by copolymerizing polymeric Y-series acceptors with congeneric molecules (TYTz-4F) that function as pendant structures. These PAs, PY-TYTz-x (x = 2.5, 5, and 10), exhibit similar absorption and energy levels but possess reduced electron mobilities and inferior molecular aggregation compared to PY-TYTz-0 (named PY-V-gamma). Among these PA-based devices, power conversion efficiencies (PCEs) of 18.14% and 16.17% were achieved in rigid and flexible devices, respectively, by pairing PY-TYTz-5 with PM6 as the donor. Furthermore, the analysis of morphological characteristics and physical mechanisms confirmed the abovementioned performance results and also highlighted the advantage of this design strategy in improving the mechanical robustness of the devices. Impressively, in comparison to the control PA PY-TYTz-0, PY-TYTz-5 also exhibited much better compatibility with other classical polymer donors, including PBDB-T, PM7, D18-Cl, and PTQ10, thereby resulting in significantly improved performance in corresponding devices. This work underscores the potential of constructing random terpolymerization PAs with Y-derivative acceptor pendants in improving the donor/acceptor compatibility and facilitating the performance and commercial applications of all-PSCs. A new polymer acceptor with Y-derivative pendants is designed to effectively improve donor/acceptor compatibility and blend morphology and construct high-performance binary all-polymer solar cells with a broad donor-acceptor matching tolerance.