Low-temperature solution-processed vanadium oxide as hole transport layer for efficient and stable perovskite solar cells

In recent years, great progress has been achieved in improving the power conversion efficiency (PCE) of organic-inorganic hybrid perovskite solar cells (PSCs), but the stability of PSCs is still an obstacle in their commercialization due to the limitation of efficient and stable hole transport materials. Herein, we demonstrate an alcohol-solution-based low-temperature-processed vanadium oxide (VOx) hole transport layer (HTL) for planar heterojunction PSCs. The good crystallinity and morphology of CH3NH3PbI3 grown on this amorphous VOx film is investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Due to the suitable and matching energy levels of VOx and CH3NH3PbI3, the holes generated in CH3NH3PbI3 can efficiently transfer to VOx HTL. Furthermore, VOx-HTL-based PSCs yield a PCE value of 14.5% with better stability in comparison with PEDOT:PSS-HTL-based PSCs. These results reveal that the low-temperature-processed VOx films can be employed as the HTL for efficient and stable PSCs.