Carbon materials in halide perovskite solar cells and photoelectrochemical water splitting

Abstract In halide perovskites, the hole transport material determines the high charge transport properties. Therefore, highly efficient hole transport materials have been developed. On the other hand, the hole transport layer is sensitive to environmental conditions such as water and oxygen due to ionic treatments such as cation doping, and the issue of environmental durability has always been raised. Carbon materials are promising as new hole transport layers in halide perovskite materials because they are hydrophobic materials and have hole transport properties. Furthermore, various carbon materials can be used and are expected to be an alternative material for expensive hole transport layers. Leveraging the advantages of carbon materials, their combination with halide perovskites has been applied to fabricate air‐stable solar cells. Moreover, the excellent water resistance of carbon materials has enabled the development of photoanodes that use halide perovskites as the photosensitive layer.