Zero-valent tin nanoparticles for reliability in Sn-containing perovskites

Tin-lead (Sn-Pb) mixed halide perovskites are imperative to fabricate high-performance all-perovskite tandem solar cells. However, the rapid, light-induced oxidation of Sn 2+ severely limits their operational longevity. Here, we uncover an effective antioxidant strategy using zero-valent tin nanoparticles to intercept these degradation pathways. The zero-valent tin nanoparticles exhibit a potent reductive capacity that eliminates deleterious Sn 4+ impurities during precursor processing and thin film crystallization via a redox-shutting mechanism. Operando photoluminescence and stability analyses substantiate that zero-valent tin nanoparticles form robust Sn–I bonds with photo-generated I 2 species, thereby decoupling the I 2 -mediated Sn 2+ oxidation cycle. Furthermore, the zero-valent tin modification facilitates photo-induced stress relaxation, leading to a transient initial efficiency enhancement. Subsequently, zero-valent tin-modified FA 0.7 MA 0.3 Sn 0.5 Pb 0.5 I 3 based inverted planar solar cells achieve a certified power conversion efficiency of 23.26% (aperture area 4.05 mm 2 ), maintaining over 90% of their initial performance after 500 hours of continuous operation at the maximum power point under AM 1.5 G illumination. Notably, the unencapsulated Sn-Pb perovskite devices exhibited environmental durability, retaining over 80% of their initial efficiency after six days of ambient exposure at 60% relative humidity. This work provides a simple yet scalable chemical approach to overcome the oxidation bottleneck, paving the way for commercially viable, stable Sn-containing perovskite optoelectronics.