Optimal perovskite vapor partitioning on textured silicon for high-stability tandem solar cells

Achieving conformal, vapor-deposited perovskite films on industry-standard textured silicon substrates with micrometer-scale pyramids remains challenging because of the complex surface partitioning of perovskite vapors and the effects of nonequilibrium organic and inorganic vapor adsorption. We incorporated 3,3,3-trifluoropropyl-trimethoxysilane to enhance substrate-organic interactions, thereby optimizing surface partitioning and balancing adsorption of perovskite vapors. Vertically uniform perovskite films with minimal phase impurities formed, and nanobeam diffraction confirmed formation of the perovskite cubic phase across different pyramid regions. The resulting tandem devices achieved a power conversion efficiency of 31.3% (1 square centimeter aperture area) and exhibited excellent operational stability, retaining 90% of their initial performance after 1400 hours of continuous 1-sun illumination at 85°C.