Epitaxial 1D electron transport layers for high-performance perovskite solar cells

We demonstrate high-performance perovskite solar cells with excellent electron transport properties using a one-dimensional (1D) electron transport layer (ETL). The 1D array-based ETL is comprised of 1D SnO₂ nanowires (NWs) array grown on a F:SnO₂ transparent conducting oxide substrate and rutile TiO₂ nanoshells epitaxially grown on the surface of the 1D SnO₂ NWs. The optimized devices show more than 95% internal quantum yield at 750 nm, and a power conversion efficiency (PCE) of 14.2%. The high quantum yield is attributed to dramatically enhanced electron transport in the epitaxial TiO₂ layer, compared to that in conventional nanoparticle-based mesoporous TiO₂ (mp-TiO₂) layers. In addition, the open space in the 1D array-based ETL increases the prevalence of uniform TiO₂/perovskite junctions, leading to reproducible device performance with a high fill factor. This work offers a method to achieve reproducible, high-efficiency perovskite solar cells with high-speed electron transport.