Electronic band structure modulation in Cs2AgInCl6 single crystals by Bi ion alloying

The tunability of the bandgap and other optical properties of Cs2AgInCl6 through Bi alloying have recently garnered increasing attention. However, the corresponding valence band structure evolution in experiments remains unclear and requires further exploration. Herein, the valence band structures of Cs2AgInxBi1 − xCl6 single crystals were measured by angle-resolved photoelectron spectroscopy using polarized extreme ultraviolet light. The shift in valence band maximum toward lower binding energies in Bi-doped Cs2AgInCl6 compared to pure Cs2AgInCl6 can be ascribed to hybridization between Cl-3p, Ag-4d, In-4d orbitals and Bi-6s orbitals, which is verified by photoemission intensity maps and density functional theory calculations. Our findings will enhance the understanding of charge carrier properties of lead-free double perovskite materials and provide a framework for improving the performance of optoelectronic devices.