Structural, elastic, electronic and optical properties of double perovskites Ba2NaXO6 (X = Cl, Br, I): First-principles study

The structural, elastic, electronic, and optical properties of double perovskites Ba2NaXO6 (X = Cl, Br, I) were investigated by first-principles calculations. The obtained results show that the three compounds can exist stably in terms of mechanical and dynamical stabilities, and three structures have anisotropy in elastic behavior. In addition, they are all direct bandgap semiconductors, and the corresponding bandgap values are 0.623 (2.4668) eV, 0.6158 (2.3476) eV, and 2.3820 (4.0947) eV from PBE (HSE06) method, respectively. Its internal chemical bonds and electronic information were also analyzed in detail by the electron localization function (ELF). In terms of optical properties, the three materials exhibit strong absorption and photoconductive properties in the UV region. In these three compounds, Ba2NaBrO6 has the preferable photovoltaic performance and conversion efficiency, making it has the potential application of optoelectronic devices in the UV region.