Critical Review of Cu‐Based Hole Transport Materials for Perovskite Solar Cells: From Theoretical Insights to Experimental Validation

Abstract

AbstractDespite the remarkable efficiency of perovskite solar cells (PSCs), long‐term stability remains the primary barrier to their commercialization. The prospect of enhancing stability by substituting organic transport layers with suitable inorganic compounds, particularly Cu‐based inorganic hole‐transport materials (HTMs), holds promise due to their high valence band maximum (VBM) aligning with perovskite characteristics. This review assesses the advantages and disadvantages of these five types of Cu‐based HTMs. Although Cu‐based binary oxides and chalcogenides face narrow bandgap issues, the “chemical modulation of the valence band” (CMVB) strategy has successfully broadened the bandgap for Cu‐based ternary oxides and chalcogenides. However, Cu‐based ternary oxides encounter challenges with low mobility, and Cu‐based ternary chalcogenides face mismatches in VBM alignment with perovskites. Cu‐based binary halides, especially CuI, exhibit excellent properties such as wider bandgap, high mobility, and defect tolerance, but their stability remains a concern. These limitations of single anion compounds are insightfully discussed, offering solutions from the perspective of practical application. Future research can focus on Cu‐based composite anion compounds, which merge the advantages of single anion compounds. Additionally, mixed‐cation chalcogenides such as CuxM1−xS enable the customization of HTM properties by selecting and adjusting the proportions of cation M.