Dynamic Strain Regulation Via Photoresponsive Fullerenes Enables High-Performance and UV-Robust Perovskite Solar Cells.

Yang, Jianfei; Wang, Han; Xu, Yunxuan; Wang, Xuanyu; Zhang, Ziling; Lee, Jinxian; Su, Jiazheng; Zhu, Yuxiang et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

The long-term stability of perovskite solar cells (PSCs) is critically undermined by degradation at the buried interface, where residual tensile strain and ultraviolet (UV) irradiation act synergistically. Here, we introduce a fullerene-based photoresponsive molecule, C<sub>60</sub>-azo, to construct an adaptive SnO<sub>2</sub>/perovskite interface. Unlike static interlayers, C<sub>60</sub>-azo functions as a dynamic molecular switch. Under UV illumination, its trans-to-cis isomerization actively generates a beneficial compressive stress to counteract residual tensile strain. Simultaneously, the light-enriched cis-isomer enhances dynamic defect passivation. This mechanochemical dual mechanism effectively mitigates UV-driven lattice distortion and chemical degradation. Consequently, the modified n-i-p PSCs achieve a power conversion efficiency of 26.60% and exhibit enhanced durability. Unencapsulated devices retain 92.7% of their initial performance after 488 h of continuous UV exposure. Encapsulated cells also maintain 94.7% efficiency after 1000 h of maximum power point tracking under continuous 1-sun-equivalent LED illumination. This work establishes dynamic photoresponsive interface engineering as a pioneering strategy for durable perovskite optoelectronics.