A first-principle study of the electronic, mechanical and optical properties of inorganic perovskite Cs2SnI6 for intermediate-band solar cells

The power conversion of perovskite solar cells has increased steadily and reached 22.1%, recently. This has led the researchers to study lead-free halide perovskite materials like Cs2SnI6 due to the toxic nature of lead used in the record-breaking organic-inorganic perovskite structures. Since the presence of an intermediate band in semiconductors leads to enhancement of efficiency of the solar cells, we have also investigated the electronic structure of Cs2SnI6, to find whether the intermediate band is likely to exist in the middle of the band gap. The computational results for the electronic band structure and density of states indicate that Cs2SnI6 contains an intermediate band (IB). Additional absorption peaks that appear in the optical spectra of this material presented in this paper explicitly confirm this. All these studies and the presence of an IB that we identified in Cs2SnI6 suggests that Cs2SnI6 may have high potential used as intermediate band solar cell material.