Perovskite-inspired materials have emerged as promising candidates for both outdoor and indoor photovoltaic applications owing to their favorable optoelectronic properties and reduced toxicity. Here, we employ the experimentally realized AgBiI4 double salt as a structural prototype and replace Bi3+ with In3+ to design a novel lead-free halide compound, AgInI4. First-principles calculations predict that AgInI4 is both chemically and dynamically stable, exhibiting a direct band gap of 1.72 eV, comparable to its bismuth analogue. However, its predicted photovoltaic performance, evaluated using the spectroscopic limited maximum efficiency metric, is lower under both solar and LED illumination. This reduction arises primarily from symmetry-forbidden optical transitions and the absence of Bi-derived 6s2 lone-pair states at the valence band maximum. High-throughput screening of the Ag-In-I ternary phase-space reveals several more stable and metastable compounds that fall into two structural families: tetrahedrally and octahedrally coordinated, with characteristic band gaps near 3.0 eV and 2.0 eV, respectively. Despite multiple synthetic attempts, the predicted AgInI4 phase could not be experimentally realized, underscoring the challenges of stabilizing indium-based halide double salts. While these materials are unlikely to serve as efficient photovoltaic absorbers, their tunable band gaps and stability make them promising candidates for charge transport and other optoelectronic applications.
@article{arxiv.2512.08721,
title = {Computational Screening and Discovery of Silver-Indium Halide Double Salts},
author = {Christos Tyrpenou and G. Krishnamurthy Grandhi and Paola Vivo and Mikaël Kepenekian and George Volonakis},
journal= {arXiv preprint arXiv:2512.08721},
year = {2025}
}