Low Temperature Solution-Processed Sb:SnO2 Nanocrystals for Efficient Planar Perovskite Solar Cells

Inorganic metal oxide electron‐transport layers (ETLs) have the potential to yield perovskite solar cells with improved stability, but generally need high temperature to form conductive and defect‐less forms, which is not compatible with the fabrication of flexible and tandem solar cells. Here, we demonstrate a facile strategy for developing efficient inorganic ETLs by doping SnO2 nanocrystals (NCs) with a small amount of Sb using a low‐temperature solution‐processed method. The electrical conductivity was remarkably enhanced by Sb‐doping, which increased the carrier concentration in Sb:SnO2 NCs. Moreover, the upward shift of the Fermi level owing to doping results in improved energy level alignment, which led to reduced charge recombination, and thus longer electron recombination lifetime and improved open‐circuit voltage (VOC). Therefore, Sb‐doping of SnO2 significantly enhanced the photovoltaic performance of planar perovskite devices by increasing the fill factor and VOC, and reducing photocurrent hysteresis, extending the potential application of low‐temperature‐processed ETLs in future flexible and tandem solar cells. Doping effect: Sb:SnO2 nanocrystalline films are successfully prepared using a low‐temperature solution‐processed method as an efficient electrontransport layer for planar perovskite solar cells. Intentional Sb‐doping is demonstrated as an effective approach to increase the electrical conductivity and upward shift the Fermi level of SnO2, leading to dramatically enhanced photovoltaic performance and suppressed hysteresis.