Electronic Modulation in Site-Selective Occupation of Quasi-2D Triangular-Lattice CsCuClBr Perovskite Probed by Surface-Sensitive Characterization.

A controllable electronic manipulation in a frustrated magnetic system such as solution-based two-dimensional (2D) all-inorganic perovskites offers a possible route for their integrations with electronic and magnetic devices for their advanced applications. Here, we perform element-specific investigations of an emergent class of quasi-2D all-inorganic perovskites CsCuClBr with (0 ≤ ≤ 4) using a combination of synchrotron-radiation photoelectron techniques. Surface- and element-sensitive X-ray absorption spectroscopy spectra of Cu edges indicate strong electronic transition that is largely influenced by their halogen content at room temperature.