Computational design of lead halide perovskite heterostructures through iodide and bromide alloying

All-inorganic lead halide perovskite solar cells have recently drawn growing attention due to their superior stability to organic counterparts and high power conversion efficiency. In this study, we use hybrid functional to assess the electronic and optical properties of [Figure presented] (where x = 0, 25, 50, 75, and 100%) compounds, employing the special quasirandom structure approach and including spin–orbit coupling. Our results show that increasing Br content leads to a corresponding increase in the bandgap, which ranges from a minimum of 1.79 eV to a maximum of 2.32 eV when Br fully replaces I. The same effect is also reflected in the optical properties, which were also examined. By substituting bromide for iodide, an optical absorption spectrum of 1.4×105cm−1 at 3.1 eV within the visible range. Our findings further reveal that the ionization energy and electron affinity of [Figure presented] are affected by bromide concentration in a different way according to its surface termination and the variations in bromide content. Because of their favorable band gap, band offset and optical properties, the findings assist developments in the construction of photovoltaic devices employing [Figure presented] alloys, which are suitable for photovoltaic devices, particularly in silicon tandem solar cells.