Unveiling the essential physical properties of indium-based thermodynamically stable delafossites XInO2 (X = Na, K) as an energy harvesting material: a systematic first-principles study

Abstract

This study examines the properties of indium-based thermodynamically delafossites, namely XInO₂ (where X = Na, K), in their trigonal phase using GGA and mBJ techniques inside the DFT framework. It proves that these materials have an apparent bandgap that is indirect. The bandgap for NaInO₂ is 1.90 (GGA-PBE), 3.98 (mBJ), and 1.80 (GGA-PBE), 3.69 (mBJ) for KInO₂. Stability was assessed using phonon band structures and molecular dynamics simulations; thermodynamic characteristics were examined using variables including heat capacity, enthalpy, entropy, and free energy. The optical characteristics of these materials were also investigated, and a range of factors, including refractive index and dielectric functions, were evaluated. Using BoltzTrap code analysis, the research looked at these material’s temperature-dependent characteristics in more detail. It focused on the materials thermal and electrical conductivities, the Seebeck coefficient, and other pertinent metrics. The first-principles calculation of the optical and thermoelectric characteristics offers a new direction for further experimental research on their use in renewable energy devices.