Synergistic Bulk and Surface Modification in Atomic Layer Deposited Tin Oxide for Efficient and Stable Perovskite Solar Cells and Modules

Atomic-layer-deposited (ALD) tin oxide (SnO 2 ) electron-transport layers (ETLs) generally underperform in n-i-p structured perovskite solar cells (PSCs) compared to solution-processed counterparts. The inherent organic residues in ALD-SnO 2 disrupt crystallinity and obstruct charge transfer, while they accelerate perovskite interfacial degradation. To address this, an invasive solution bath post-treatment is introduced by using sodium 2,3-dimercapto-1-propanesulfonate (DMPS) as the additive in the solution bath. DMPS, bearing thiol and sulfonate groups, simultaneously chelates the surface and the inner layer of the SnO 2 layer, successfully removing organic residues from the bulk and surface while suppressing water-induced morphological damage. Consequently, this synergistic modification yields champion efficiencies of 25.26% for small-size cells and 22.42% for 12.5 cm 2 mini-modules, alongside significantly enhanced operational stability. Our work offers a scalable route for integrating high-performance ALD-SnO 2 in large-area n-i-p solar modules.