First-principles study of photovoltaic and thermoelectric properties of AgBiSCl2

TL;DR

This study uses first-principles calculations to explore AgBiSCl2's potential as a dual photovoltaic and thermoelectric material, highlighting its structural, optical, and thermal properties that favor energy conversion.

Contribution

It provides a comprehensive theoretical analysis of AgBiSCl2's properties, revealing its suitability for high-performance energy devices and offering insights into its bonding and lattice dynamics.

Findings

Low lattice thermal conductivity due to weak Ag-S and Ag-Cl bonds.

High Seebeck coefficient and figure of merit at elevated temperatures.

Strong ultraviolet absorption and high dielectric constant.

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.