Electronic, optical and thermoelectric properties of halide double perovskites Rb2AgInX6 (X = Cl, Br, I)

In the last decades, lead-based perovskites have been substantially investigated due to their superior efficiency in photovoltaics. However, owing to the harmful effect of lead, the search for other environmentally friendly materials is vital. Recently, halide double perovskites have gained attention due to their environmental friendliness and potential applications in solar cells and thermoelectric devices. The energy gap, optical and thermoelectric parameters of Rb2AgIn(Cl/Br/I)(6) halide double perovskites compounds were investigated using Wien2k and BoltzTraP2 code based on DFT. The energy gap was 2.62 eV, 1.74, and 0.56 eV for Rb2AgIn(Cl/Br/I)(6) at the gamma-points, which were direct bandgaps. More states were localized near the upper valence band, closer to the fermi energy, than near the lower conduction band, suggesting that Rb2AgIn(Cl/Br/I)(6) was p-type. The fundamental edge of absorption arises at 2.48 eV, 1.67 eV, and 0.45 eV for Rb2AgIn(Cl/Br/I)(6). The optical bandgaps calculated using the Tauc plot were 2.59 eV, 1.7 eV, and 0.49 eV for Rb2AgIn(Cl/Br/I)(6). The first absorption band illustrates that these halide double perovskite compounds show high alpha omega 20 cm(-3), 1.72 x 10(20) cm(-3), and 8.37 x 10(19) cm(-3) for Rb2AgInCl6, Rb2AgInBr6 and Rb2AgInI6 respectively. Large Seebeck coefficients with high thermoelectric efficiencies (greater than unity at room temperature) were observed for these halide double perovskites compounds.

Automated summary

In recent decades, lead-based perovskites have been extensively studied for their high efficiency in photovoltaics. However, due to the harmful effects of lead, finding environmentally friendly alternatives is crucial. Halide double perovskites have gained attention as they are environmentally friendly and hold potential applications in solar cells and thermoelectric devices. The energy gap, optical, and thermoelectric properties of Rb2AgIn(Cl/Br/I)(6) halide double perovskite compounds were investigated using DFT-based Wien2k and BoltzTraP2 code. These compounds exhibited direct bandgaps of 2.62 eV, 1.74 eV, and 0.56 eV at the gamma points. They were found to be p-type, with more localized states near the upper valence band. The absorption edge occurred at 2.48 eV, 1.67 eV, and 0.45 eV, and the optical bandgaps were calculated as 2.59 eV, 1.7 eV, and 0.49 eV. These halide double perovskite compounds demonstrated high alpha omega values of 20 cm(-3), 1.72 x 10(20) cm(-3), and 8.37 x 10(19) cm(-3) for Rb2AgInCl6, Rb2AgInBr6, and Rb2AgInI6 respectively. They also displayed large Seebeck coefficients and high thermoelectric efficiencies (greater than unity at room temperature).