Tailoring of band gap to tune the optical and thermoelectric properties of Sr1-xBaxSnO3 stannates for clean energy; probed by DFT

[Display omitted] •Tuning of band gap from ultraviolet to visible region.•Absorption in visible region increase their potential for solar cells.•Figure of merit is maxima at 50% doping of Ba.•The studied Stannates are tuned for optical and thermoelectric characteristics. The perovskite stannates Sr1-xBaxSnO3 (x = 0.0, 0.25, 0.50, 0.75, 1.0) are studied theoreticaly to explore them for energy applications. The doping of Ba changes the structural behavior of studied compounds. The studied compound has direct band gap at x = 0.25 and 0.75 while indirect band gap at x = 0.0, 0.50 and 1.0. The band gap tuned from ultraviolet to visible region (4. eV to 1.7 eV) but the direct nature x = 0.25 and 0.75 increases their potential solar cell applications at specific composition. The reported optical properties show the maximum absorption of light and refractive index is favourable for solar cells. Finally, the transport properties have been elaborated by solving the Boltzmann transport equation. The doping composition Sr0.50Ba0.50SnO3 increases the figure of merit up to 0.74 which is suitable for thermoelectric applications.