Study of structural, electronic, mechanical, optical and thermoelectric properties of As based halide-perovskites Ba3AsX3 (X= F, Cl): A first-principles insights

Here in, we study the structural, electronic, mechanical, optical and thermoelectric properties of As based Ba3AsX3 (X = F, Cl) using the density functional theory. The result show that both materials crystallize into cubic structure. The tolerance factor and octahedral factor indicates that both materials have stable perovskite structure. The obtained optimize lattice constant are 6.12 ?, and 6.50 ?, for Ba3AsF3 and Ba3AsCl3 respectively. The phonon dispersion curves show that both materials are dynamically stable. The electronic study reveals that both materials have semiconductor having band gap of 2.27eV and 1.73eV for Ba3AsF3 and Ba3AsCl3 respectively. Elastic constants are computed and found that both materials are mechanical stable. Furthermore, elastic study presents that both materials are ductile and have anisotropic nature. The optical results show that both materials have excellent optical absorption. It is observed that relaxation time for Ba3AsF3 is longer than that of Ba3AsCl3. Thermoelectric properties such as Seebeck coefficient, electrical conductivity electronic thermal conductivity, power factor and figure of merit are calculated for both materials. It is observed that for both materials Seebeck have almost same maximum value of 1.55 x 10-3 V/K at 300K. The electrical conductivity is found to be greater for Ba3AsF3 than Ba3AsCl3. The figure of merit ZT value is found 1.53 for Ba3AsF3 while 1.23 for Ba3AsCl3 at 700K. From obtained results it is concluded that these materials can be an excellent candidate for thermoelectric and optoelectronic applications.