Physical properties of double perovskites Rb2XCl6 (X= Sn, Te, Zr): Competitive candidates for renewable energy devices

Ab-initio computations are performed to analyze the Lead-free double perovskites Rb2XCl6 (X = Sn, Te, Zr) for solar cells and renewable energy. The FP-LAPW method has been adopted to compute the mechanical, optoelectronic and thermoelectric properties. The stability of the three compounds is verified through the elastic constants ensuring the ductility and the anisotropic nature of the double perovskites compounds. Both compounds Rb2TeCl6 and Rb2ZrCl6 have indirect band gap equal 2.54 eV, 3.46 eV respectively, but Rb2SnCl6 compound have direct band gap equal to 2.40 eV in the near visible region, which make them potential candidates for visible light solar cells. The optical spectra have been elaborated in terms of dielectric constants, absorption of light, refractive index, and reflection of light. The maximum absorption bands are recorded in the wavelength range of 620 nm–310 nm. Finally, thermoelectric properties are calculated by BoltzTraP code, which depicts high values of Seebeck coefficient and low thermal conductivity. Therefore, the above said parameters ensure their importance for renewable energy. •The electronic, elastic, optical and thermoelectric properties of Rb2XCl6 (X = Sn, Te, Zr) compounds are investigated for the first time.•The stability of the three materials is ensured through the study of mechanical, structural and thermal properties.•The band structures obtained have showed semiconductor behavior with indirect energy band gap for Rb2SnCl6 and Rb2TeCl6 and direct ban gap for Rb2ZrCl6.•Optical properties demonstrate the use of the materials in optoelectronic and energy devices.•Transport properties of Rb2XCl6 (X = Sn, Te, Zr) compounds are investigated showing efficient results.