Ultrathin Cu2O as an efficient inorganic hole transporting material for perovskite solar cells

Abstract

We demonstrate that ultrathin P-type Cu₂O thin films fabricated by a facile thermal oxidation method can serve as a promising hole-transporting material in perovskite solar cells. Following a two-step method, inorganic–organic hybrid perovskite solar cells were fabricated and a power conversion efficiency of 11.0% was achieved. We found that the thickness and properties of Cu₂O layers must be precisely tuned in order to achieve the optimal solar cell performance. The good performance of such perovskite solar cells can be attributed to the unique properties of ultrathin Cu₂O, including high hole mobility, good energy level alignment with CH₃NH₃PbI₃, and longer lifetime of photo-excited carriers. Combining the merits of low cost, facile synthesis, and high device performance, ultrathin Cu₂O films fabricated via thermal oxidation hold promise for facilitating the developments of industrial-scale perovskite solar cells.