SCHEDULED MAINTENANCE
A first-principles study on the optoelectronic properties of mixed-halide double perovskites Cs2TiI6−xBrx
Abstract
All-inorganic double perovskites as promising photovoltaic materials have received great attention in recent years. In this work, the structural, mechanical, electronic, and optical properties of mixed-halide double perovskites Cs2TiI6−xBrx (x = 0, 2, 4, and 6) were studied by using first-principles calculations. The calculated lattice parameters of Cs2TiI6−xBrx agree well with the reported experimental values. The calculated results have confirmed that these compounds are thermodynamically stable. Moreover, these mixed-halide double perovskites can easily be converted into thin films based on their unique mechanical properties. The obtained band gaps of the Cs2TiI6−xBrx systems using the PBE+U method have better matched with the experimental values. When the Br content increases, the band gap of Cs2TiI6−xBrx increases gradually, which leads to a decreased optical performance in the visible light region. Based on a suitable direct band gap and strong absorption coefficient, Cs2TiI2Br4 is an ideal potential material for single-junction solar cells.
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