Facile Fabrication of SnO₂ Nanorod Arrays Films as Electron Transporting Layer for Perovskite Solar Cells

As the vital competent in high performance perovskite solar cells (PSCs), the inorganic metal oxide electron transporting materials (ETMs) with tailored architectures are responsible for extracting and transporting photogenerated electrons and preventing the recombination effectively. Here, a facile hydrothermal method is demonstrated for the growth of highly crystalline and uniform 1D SnO₂ nanorod arrays (SR) with excellent optical property, which are further successfully exploited as ETMs in PSCs. Both length and diameter of 1D SR are tuned carefully by optimizing the hydrothermal process. Power conversion efficiency (PCE) as high as 16.7% can be obtained for PSCs based on these SR. Furthermore, a graded heterojunction (GHJ) configuration was built by intercalating a TiO₂ thin interlayer to improve the band alignment between perovskite and SR, which pushes the PCE to 18.7% with better ambient stability. This work demonstrates that the SR can act as a promising candidate for ETM in PSCs, and provides a workable stategy to improve the performance of PSCs.