Decoupling the Trade-Off between Efficiency and Mechanical Properties in Non-Halogen Solvent-Processed All-Polymer Photovoltaics

Herein, we report a synergistic ternary strategy to decouple the inherent trade-off between efficiency and mechanical properties in all-polymer solar cells (all-PSCs) processed from nonhalogenated solvents. By incorporating a high-molecular-weight polymer acceptor N2200 into the PM6/PY-IT system via a layer-by-layer (LbL) approach, we demonstrate that acceptor microstructure regulation serves as a pivotal handle for concurrently boosting photovoltaic performance and mechanical robustness. The optimized ternary device achieves a remarkable power conversion efficiency (PCE) of 19.08%, significantly surpassing the binary counterpart (17.56%) and ranking among the highest for eco-friendly processed all-PSCs. More importantly, this high efficiency is accompanied by a dramatically enhanced elastic modulus, which increases from 2.98 to 8.66 GPa. Comprehensive characterizations reveal that N2200 induces cascade energy alignment, promotes exciton dissociation, and optimizes molecular packing, thereby facilitating efficient charge generation and transport while suppressing nonradiative recombination. Crucially, the same microstructural regulations contribute to superior mechanical toughness, as confirmed by nanoindentation tests. This work provides a morphological design principle to break the efficiency-robustness bottleneck, paving the way for the application of high-performance all-PSCs in flexible and wearable electronics.