Physical, optoelectronic and thermoelectric characteristics of double perovskite (Sr₂ScBiO₆) for green energy technology using <i>ab initio</i> computations

Abstract

This work presents the investigation of physical characteristics including structural, electronic, elastic, optical and thermoelectric, of the double perovskite (DP) oxide Sr₂ScBiO₆ with the aid of the FP-LAPW method, dependent on DFT combined with BoltzTraP code. To incorporate the inclusion of exchange as well as correlation effects, approximations like LDA and three different forms of GGA [PBE-GGA, WC-GGA & PBEsol-GGA] are applied. The mBJ-GGA method including spin-orbital coupling (SOC) & not including SOC was utilised in this investigation and it was carried out in the WIEN2k code. In addition, the TB-mBJ exchange potential analysis classified Sr₂ScBiO₆ as having a p-type semiconducting nature with an indirect bandgap value of 3.327 eV. Additionally, the mechanical properties analysis and the related elastic constants demonstrate the anisotropic nature of Sr₂ScBiO₆ with decent mechanical stability. Apart from that, the Sr₂ScBiO₆ was considered a brittle non-central force solid with dominant covalent bonding. The varying optical parameter evaluations highlighted the potential use of Sr₂ScBiO₆ in visible-light (vis) and ultraviolet (UV)-based optoelectronic devices. Moreover, the semiconducting nature of Sr₂ScBiO₆ was verified through its thermoelectric response, which revealed that the charge carriers mostly consist of holes. Over a wide temperature range (100-1200 K), several transport metrics like the Seebeck coefficient (<i>S</i>), electrical conductivity (<i>σ</i>/<i>τ</i>), thermal conductivity (<i>κ</i>/<i>τ</i>), and power factor (PF) are investigated. An optimal value of figure of merit (<i>ZT</i>) ∼ 0.62 at <i>T</i> = 1200 K is accomplished. The extremely lower value of thermal conductivity as well as higher electrical conductivity leads to a higher figure of merit of the investigated system. The Sr₂ScBiO₆ verified a high <i>ZT</i> value, confirming that the material would be beneficial in renewable energy and thermoelectric (TE) applications.