Lowerature solution-processed tin oxide as an alternative electron transporting layer for efficient perovskite solar cells

Lead halide perovskite solar cells with the high efficiencies typically use higherature processed TiO₂ as the electron transporting layers (ETLs). Here, we demonstrate that lowerature solution-processed nanocrystalline SnO₂ can be an excellent alternative ETL material for efficient perovskite solar cells. Our best-performing planar cell using such a SnO₂ ETL has achieved an average efficiency of 16.02%, obtained from efficiencies measured from both reverse and forward voltage scans. The outstanding performance of SnO₂ ETLs is attributed to the excellent properties of nanocrystalline SnO₂ films, such as good antireflection, suitable band edge positions, and high electron mobility. The simple lowerature process is compatible with the roll-to-roll manufacturing of low-cost perovskite solar cells on flexible substrates.