Probing the electronic, optical and transport properties of halide double perovskites Rb2InSb(Cl,Br)6 for solar cells and thermoelectric applications

Halide-based double perovskites have recently been promoted as high-performing semiconductors for photovoltaic and thermoelectricity applications owing to their outstanding efficiency, non-toxicity and ecological stability. In the framework of this research, we have systematically investigated the structural, mechanical, electronic, optical, and thermoelectric properties of Rb 2 InSb ( Cl , Br ) 6 double halide perovskites. Based on Born stability and tolerance factor criteria, we have found that Rb 2 InSb ( Cl , Br ) 6 are mechanically and structurally stable. Furthermore, we have performed a comprehensive evaluation of the electronic, optoelectronic, and thermoelectric characteristics. From the electronic band structure results, Rb 2 InSbCl 6 and Rb 2 InSbBr 6 exhibit direct semiconducting band gaps of 1.41 ​eV and 0.53 ​eV, respectively. The optical parameters of Rb 2 InSb ( Cl , Br ) 6 reveal that our active structures have a higher dielectric constant, with maximum absorption in the visible range reaching over 5.68 ​× ​10 5 ​cm −1 and high optical conductivity (2.19 fs −1 for Rb 2 InSbCl 6 and 2.14 fs −1 for Rb 2 InSbCl 6 ). Moreover, the maximum limited spectroscopic efficiency reaches an impressive value of approximately 28.0% for Rb 2 InSbBr 6 and 33.7% for Rb 2 InSbCl 6 . The thermoelectric properties were accurately calculated using the BoltzTraP simulation package. The obtained results reveal a significant electrical conductivity, a strong Seebeck coefficient (S ​≈ ​2756 μVK −1 ​at 300 ​K), and an average figure of merit close to one for both structures (ZT ​≈ ​1). Our findings suggest the versatility of these materials and could be used for a wide range of applications, including commercial solar cells and thermoelectricity. • Perovskites Rb 2 InSb(Cl, B) 6 exhibit high mechanical, thermodynamic and structural stability. • The direct narrowband gaps of Rb 2 InSbBr 6 (0.53 ​eV) and Rb 2 InSbCl 6 (1.41 ​eV) make the materials more suitable. • Potential candidates for sustainable and environmentally friendly energy. • The high conversion efficiency of about 33.7%, and high thermoelectric figure of merit of about one.