Computational insights into exciton localization and luminescence mechanisms in Cu-Ag lead-free halides
Phys. Rev. B 113, 035138 – Published 21 January, 2026
DOI: https://doi.org/10.1103/m1wx-n2my
Abstract
This work aims to elucidate the microscopic origins of various photoluminescence emissions in copper- and silver-based halide compounds by means of first-principles calculations. Our density functional theory based analysis reveals that Cu pair and Ag pair self-trapped excitons (STEs) exhibit distinct structural configurations and excited-state behaviors, with Ag pair STEs showing pronounced electrophilicity. Defect states, including interstitial iodine and halogen vacancies, play decisive roles in quenching or enabling emission. Cation substitution not only modifies STE configurations but can also enable the coexistence of multiple STE types within a single lattice, offering a route to tunable photoluminescence. These findings clarify the contrasting roles of Cu and Ag pairs and provide guidance for tailoring halide emitters through targeted cation substitution and defect engineering.
