A comprehensive DFT analysis of the physical, optoelectronic and thermoelectric attributes of Ba2lnNbO6 double perovskites for eco-friendly technologies

•To analyze the structural, mechanical, electronic, optical, and transport properties of the double perovskite Ba2InNbO6 compound using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method.•To determine the stability of the Ba2InNbO6 compound by its mechanical properties, formation energy, and cohesive energy reveal that compounds are stable.•Computed the electronic properties exhibit a indirect band gap.•The thermoelectric characteristics are examined throughout a temperature range of 100 K to 1200 K and chemical potential. Within the framework of density functional theory (DFT), as executed in WIEN2k as well as semi-classical Boltzmann transport theory, we reported structural, electronic, elastic, optical, thermoelectric, and thermodynamic properties of the double perovskite compound Ba2InNbO6. To employ the exchange–correlation potential, local density approximation (LDA), the generalized gradient approximation (GGA) with Perdew, Burke and Ernzerhof (PBE) and the modified Becke–Johnson (mBJ) potential is considered. The elastic constants are calculated to check the mechanical stability. The electronic calculations show semiconducting nature with a wide band-gap (3.63 eV) for Ba2InNbO6. The optical properties such as complex dielectric constant ε(ω), refractive index n(ω), reflectivity R(ω), absorption coefficient α(ω), optical conductivity σ(ω) and energy loss function L(ω) described with the incidence frequency. The absorption spectrum shows the behaviour of common semiconductors. The Seebeck coefficient (S) as well as electrical conductivity (σ/τ) also demonstrates the semiconducting nature of the studied compounds by holes having highest particles. The PF was 1.85 × 1012 W K−2 m−1 s−1 at 1200 K and thermodynamic studies, the heat capacity as well as Gruneisen parameter were guessed. Based on obtained results we can ensure that the double perovskite compound Ba2InNbO6 is well suitable for optical and thermoelectric applications.