First-principles study of photovoltaic and thermoelectric properties of AgBiSCl2

Abstract

This work systematically investigates the potential of the hybrid anion semiconductor AgBiSCl2 for photovoltaic and thermoelectric applications, aiming to provide theoretical guidance for high-performance energy conversion devices. Structural analysis reveals favorable ductility and a relatively low Debye temperature. Analysis of interatomic interactions indicates that Ag-S and Ag-Cl bonds are relatively weak, resulting in local structural softness and enhanced lattice anharmonicity. These weak bonds facilitate phonon scattering and give rise to low-frequency localized rattling vibrations primarily associated with Ag atoms, contributing to reduced lattice thermal conductivity. In contrast, Bi-S bonds exhibit stronger, directional interactions, which help stabilize the overall structure. The coexistence of weak bonding and strong lattice coupling enables favorable modulation of thermal transport properties.Optically, AgBiSCl2 possesses a high static dielectric constant and exhibits strong absorption in the ultraviolet region. In terms of thermal transport, phonon spectrum exhibit mode hardening with temperature increasing. The localized Ag vibrations intensify the anharmonicity, reducing phonon lifetimes and group velocities.For electronic transport, the p-type material maintains a higher Seebeck coefficient than the n-type, while the latter shows greater electrical conductivity. At 700 K, the figure of merit reaches 0.77 for p-type and 0.69 for n-type AgBiSCl2, indicating promising high-temperature thermoelectric performance.In summary, AgBiSCl2 exhibits excellent potential for dual photovoltaic and thermoelectric applications. Its unique bonding features and lattice response mechanisms offer valuable insights into designing multifunctional energy conversion materials.