Thermally Evaporated SnO ₂ Buffer Layers for p–i–n Perovskite Solar Cells

Tin(IV) oxide (SnO 2 ) thin films are commonly employed as buffer layers in p–i–n perovskite solar cells that feature transparent electron-collecting contacts, to protect underlying layers from electrode sputtering damage. While SnO 2 is typically deposited via atomic layer deposition, we demonstrate here its much simpler fabrication by thermal evaporation at room temperature without any postdeposition treatment. The evaporated films exhibit oxygen deficiency that increases with film thickness. Importantly, when integrated into p–i–n solar cells, the SnO 2 vacuum deposition process effectively mitigated sputtering-induced degradation during electrode deposition, retaining pristine perovskite/C 60 layers. These findings establish thermally evaporated SnO 2 as a viable alternative to atomic-layer-deposited counterparts for use as buffer layers in p–i–n perovskite solar cells.