Low-temperature solution-processed SnO electron transport layer modified by oxygen plasma for planar perovskite solar cells

SnO has attracted significant attention as an electron transport layer (ETL) because of its wide optical bandgap, electron mobility, and transparency. However, the annealing temperature of 180 °C-200 °C, as reported by several studies, for the fabrication of SnO ETL limits its application for flexible devices. Herein, we demonstrated that the low-temperature deposition of SnO ETL and further surface modification with oxygen plasma enhances its efficiency from 2.3% to 15.30%. Oxygen plasma treatment improves the wettability of the low-temperature processed SnO ETL that results in a larger perovskite grain size. Hence, oxygen plasma treatment effectively improves the efficiency of perovskite solar cells at a low temperature and is compatible with flexible applications.