Low-Temperature-Processed Monolayer Inverse Opal SnO₂ Scaffold for Efficient Perovskite Solar Cells

Organic-inorganic halide perovskite solar cells (PSCs) have attracted tremendous attention in the photovoltaic field due to their excellent optical properties and simple fabrication process. However, the recombination of photogenerated electron-hole pairs at the interface severely affects the power conversion efficiency (PCE) of the PSCs. Herein, a monolayer of inverse opal SnO₂ (IO-SnO₂ ) is synthesized via a template-assisted method and used as a scaffold for perovskite layer (PSK). The porous IO-SnO₂ scaffold increases the contact area and shortens the transport distance between the electron transport layer (ETL) and PSK. Ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy results indicate that the built-in electric field is enhanced with IO-SnO₂ scaffold, strengthening the driving force for charge separation. Femtosecond transient absorption spectroscopy measurements reveal that the IO-SnO₂ scaffold facilitates interfacial electron transfer from PSK to ETL. Based on the above superiorities, the IO-SnO₂ -based PSCs exhibit boosted PCE and device stability compared with the pristine PSCs. This work provides insights into the development of novel scaffold layers for high-performance PSCs.