Simultaneously improved stretchability, stability, and output power in solar cells via entanglement control

Intrinsically stretchable solar cells have gained significant attention as potential power sources for wearable devices due to their light weight and flexible nature. However, designing active layers that are simultaneously highly stretchable, efficient, and stable for wearables remains challenging. Herein, we propose an entangled polymer additive strategy to address this issue and enhance both photovoltaic performance and mechanical stability of active layers under large strains. By optimizing the entangled film morphology, we have successfully developed intrinsically stretchable all-polymer solar cells with exceptional thermal stability (T₈₀ > 10 000 h), stretchability (strain at 80% efficiency surpasses 50%), mechanical robustness (1000 cycles under 50% strain) and improved output power, which has rarely been observed in any type of solar cell. Furthermore, we have established correlations between entanglement, miscibility, morphology, and mechanical models for ternary blends. The strategy can also improve the mechanical properties of the PM6:PY-IT based ternary system. This knowledge is instrumental in advancing the development of intrinsically stretchable and durable photovoltaic devices.