Pressure Response of Photoluminescence in Cesium Lead Iodide Perovskite Nanocrystals

In this paper, we address the phase stability and the relationship between optical gap and structural perturbations in cesium lead halide nanocrystals. We report photoluminescence (PL) spectra for cesium lead iodide (CsPbI3) perovskite nanocrystals under hydrostatic pressures up to 2.5 GPa. The peak position of the CsPbI3 PL shifts as a function of pressure. Initially, the PL shifts to lower energies, until a reversal occurs near 0.33 GPa. At higher pressures, the PL peak position shifts to the blue until PL vanishes above 2.5 GPa. We explain the pressure response with different modes of deformation of the perovskite crystal structure.