Low-temperature processed SnO2 compact layer by incorporating TiO2 layer toward efficient planar heterojunction perovskite solar cells

Abstract Inorganic metal oxide electron-transport layers have the potential to promise perovskite solar cells with improved stability and high efficiency, but generally require high temperature to enhance conductivity and reduce defect. Here, low-temperature solution-processed inorganic SnO 2 -TiO 2 composite layer for efficient planar heterojunction perovskite solar cells is demonstrated. The SnO 2 -TiO 2 composite layer brings better bandgap matching at the perovskite/FTO interface that facilitates charge extraction and reduces surface recombination. Cyclic voltammetry, steady-state photoluminescence spectroscopy and electrical impedance spectroscopy were conducted to reveal the energy band alignment and charge carrier dynamics. The SnO 2 -TiO 2 composite films based solar cells acquire a high power conversion efficiency (PCE) of 14.8%, which is higher than PCEs of devices based on individual SnO 2 layer and sintered TiO 2 layer.