Kalyani, M.Ananthram, K.S.Saha, S.Ninawe, P.Tarafder, K.Ballav, N.2026-02-032025Inorganic Chemistry, 2025, 64, 9, pp. 4378-4386201669https://doi.org/10.1021/acs.inorgchem.4c05012https://idr.nitk.ac.in/handle/123456789/20375Halide perovskites have recently evolved as attractive materials with enormous technological significance due to synthetic control over the structure-property relationship. Halide perovskites are often realized to be either electrical insulators or semiconductors. We present an unusual metal-like conduction (thermally deactivated) in a Pb-free all-inorganic halide double perovskite, Cs<inf>2</inf>AgSbCl<inf>6</inf>. The experimental results were understood using density functional theory studies, combined with molecular dynamics simulations and electron localization function calculations, revealing retention of the predominant ionicity of the Ag-Cl bond and an increase in the covalency of the Sb-Cl bond at an elevated temperature, which resulted in a significant change of the electronic band structure, including the density of states, thereby exhibiting an intricate balance of ionicity and covalency. A significant modulation of the electrical conductivity (more than 3 orders of magnitude) without any noticeable structural change will stimulate the investigation of hitherto unknown electronic phase transitions in halide double perovskites. Additionally, light-induced unidirectional rectification of current in Cs<inf>2</inf>AgSbCl<inf>6</inf> was ascribed to a dynamic internal polarization effect. © 2025 American Chemical Society.Antimony compoundsCarrier concentrationCesium compoundsElectric rectifiersGallium phosphideGermanium compoundsPhotodissociationSemiconductor insulator boundariesWide band gap semiconductorsCovalenciesDouble perovskitesElectrical insulatorsHalide perovskitesInorganic halidesIonicitiesPb-freeStructure-properties relationshipsSynthetic controlTechnological significancePerovskitehalideleadmetalperovskitearticlecontrolled studydensity functional theoryelectric conductivitymolecular dynamicspharmacologyphase transitionpolarizationsemiconductortemperature