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 (SnO2) 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-SnO2 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 SnO2 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 cm2 mini-modules, alongside significantly enhanced operational stability. Our work offers a scalable route for integrating high-performance ALD-SnO2 in large-area n-i-p solar modules.