SnO2 Modified Mesoporous ZrO2 As Efficient Electron-Transport Layer for Carbon-Electrode Based, Low-Temperature Mesoscopic Perovskite Solar Cells

SnO2 modified mesoporous ZrO2 is used to replace the mesoporous TiO2 layer and serves as a kind of mesoporous electron-transport layer during the low-temperature fabrication of mesoscopic perovskite solar cells that are based on carbon electrode. X-ray/ultraviolet photoelectron spectroscopy studies and electrical test observe that SnO2 modification brought down the work function while increasing the conductivity of the mesoporous ZrO2. Transient photovoltage/photocurrent decay curves, impedance spectroscopy, and photoluminescence mapping show that after the bottom layer of ZrO2 is modified by SnO2, the charge extraction process is accelerated while recombination is retarded. This modification helps to increase the power conversion efficiency from 4.70 (±0.85)% to 10.15 (±0.35)%, along with the optimized efficiency at 13.37% (AM1.5G, 100 mW/cm2) for the low-temperature devices. In addition, the effects of modification layers of SnO2 on the power conversion properties are carefully studied. This study shows that SnO2 modified mesoporous ZrO2 could serve as an efficient electron-transport layer for the low-temperature mesoscopic devices.