| Abstrakt: |
We have systematically investigated the structural, electronic and optical properties of perovskite derivative Cs3Sb2I9 under various pressures utilizing first-principles calculations within density functional theory. The calculated lattice constants are in good agreement with previous results. From the analysis of electronic properties, we concluded that Cs3Sb2I9 is a direct band gap semiconductor with a value of 1.92 eV. The research of bonding properties shows that the bonds of Cs3Sb2I9 are covalent bonds, which can increase the stability of the compound. It is noteworthy that the band gap decreases with the pressure increase in the range of 0–20 GPa, and the valence band maximum (VBM) with hybrid characteristics and mainly consisted of I 5p orbital and a small amount of Sb 5s orbital. Further, we have evaluated for the first time dielectric and optical properties of this compound. In the energy range from 0 to 20 eV, all the optical spectra shift to lower energy as the pressure increases, and the decrement of the absorption coefficient corresponds to the change of the band gap. We found that the optical properties of perovskite derivative Cs3Sb2I9 undergo a red shift with increasing pressure. This is the first quantitative theoretical prediction of the optical properties of Cs3Sb2I9 compound, and it still awaits experimental confirmation. [ABSTRACT FROM AUTHOR] |
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