Layer-dependent optoelectronic property for all-inorganic two-dimensional mixed halide perovskite Cs2PbI2Cl2 with a Ruddlesden-Popper structure

Two-dimensional (2D) organic-inorganic hybrid Ruddlesden-Popper (RP) perovskite materials have attracted considerable attention due to their unique performance and enhanced stability for photovoltaic and photoluminescent devices. However, the optoelectronic properties of 2D all-inorganic RP perovskites remains unclear because of hard-to-experiment synthesis. Therefore, the two-dimensionality how to affect the photoelectric properties of all-inorganic perovskites remains unclear. In this study, we investigate the electrical and optical properties, including the band structures, carrier mobility, optical absorption spectra, and exciton-binding energies for newly synthesized all-inorganic 2D-layered RP perovskite Cs2PbI2Cl2 using density functional theory. The results demonstrate the thickness-dependence of photoelectric properties in 2D-layered RP perovskite Cs2PbI2Cl2. The carrier mobilities and absorption coefficients in the visible spectrum of Cs2PbI2Cl2 are smaller than those of MAPbI3 and Si crystal photovoltaic materials, whereas the exciton-binding energies increase with the decrease in the number of layers, which are obviously higher than those of MAPbI3 and Si crystal. The results show that Cs2PbI2Cl2 is a good material for luminescent devices rather than for photovoltaic cells. This study provides a theoretical basis for other ultra-thin two-dimensional perovskite materials with potential applications in photoluminescent devices.