Thermal, Optoelectronic and Thermoelectric Properties of Inorganic Double Perovskites Semiconductors Cs2(Sn, Pt, Te)I6 For Application as Intermediate-band Solar Cells

Abstract

First-principle calculations using the Wien2k code and the GGA-mBJ exchange potential were used in the study of the thermodynamic, dynamic, chemical and elastic stability, as well as the electronic, optical and thermoelectric properties of Cs2(Sn, Pt, Te)I6. The presence of an intermediate band in Cs2(Sn, Pt, Te)I6 semiconductors confirmed by absorption peaks appeared at photon energy corresponding to the band gap enhances the efficiency of solar cells. The ideal band gap, high dielectric constants and optimal absorption make the double perovskites under study perform well in solar cells. The calculated minimum formation energy, Helmholtz free energy and phonon modes through the first Brillouin zone for the investigated Cs2(Sn, Pt, Te)I6 family confirm their thermal, thermodynamic and dynamic stability. The acoustic phonon contribution modes come from the Cs-6s and I-5p electrons, while the Pt-6s, Sn-5p, Te-5p and I-5p electrons participate in the optical phonon modes. The narrowness of the upper valence band and the band gap in the visible region for advantage this double perovskite in energy harvesting. The geometric Goldschmidt tolerance factor value between 0.8 and 1.0 and octahedral factor 0.41 indicate that double perovskite is more stable.