Giant Band Gap Narrowing under Hydrostatic Pressure in (4FP)SnI Halide Perovskite.

One of the most intriguing properties of hybrid halide perovskites is their structural softness. The interplay between organic and inorganic sublattices leads to a multitude of physical phenomena that are not observed in conventional semiconductors such as III-V materials. One among these is the exceptional band gap tunability under hydrostatic pressure. In this context, tin-based perovskites exhibit a more pronounced effect than their lead-based counterparts. Here, we report on one of the largest band gap tunabilities in this material family. The studied material, layered tin-based (4FP)SnI perovskite, exhibits an exceptionally strong pressure sensitivity, with a band gap shift of up to -160 meV/GPa at room temperature. Combined experimental and computational studies reveal that its band gap dependence on pressure remains linear in the 0-5 GPa range, making (4FP)SnI highly attractive for pressure-sensor applications.