Electronic structures of ABX3 perovskite crystals with a monovalent copper ion as the A-site cation

A study was performed on the electronic structures and properties of perovskite compounds with the chemical formula ABX3 and the monovalent copper ion (Cu+) as the A-site cation. Most Cu+-based perovskite chlorides (CuMCl3, where M denotes an element) had lower total energies than cesium (Cs)-based perovskite crystals. The energy gaps of CuMCl3 perovskites with B-site cations spanning chromium (Cr) to zinc (Zn) were close to the ideal value for photovoltaic materials. The calculated carrier effective mass ratios indicated that CuMCl3 should have a similar or higher carrier mobility than CsPbCl3 (Pb=lead). Unlike Cs-based perovskites, the electron orbitals of Cu and the MCl6 octahedron overlap, suggesting that the Cu+ at the A-site should affect the stability of the crystal structure and the carrier mobility. The Cu+ ion can be used as the A-site cation in ABX3 perovskites to tune the composition of all-inorganic perovskite crystals and thereby increase the diversity of physical properties.