Cesium-Doped Vanadium Oxide as the Hole Extraction Layer for Efficient Perovskite Solar Cells

In this study, we report the utilization of low-temperature solution-processed Cs-doped VO_X thin films as the hole extraction layers (HELs) in perovskite solar cells (PSCs). It is found that the VO_X:yCs (where y is the mole ratio of Cs versus V and y = 0.1, 0.3, and 0.5) thin films possess better electrical conductivities than that of the pristine VO_X thin film. As a result, the PSCs incorporated with the VO_X:yCs HEL exhibit large fill factors and high short-circuit currents, with consequently high power conversion efficiencies, which is more than 30% enhancement as compared with pristine VO_X HEL. Our studies provide a facial way to enhance the electrical conductivity of the hole extraction layer for boosting device performance of perovskite solar cells.