High-Pressure Phase Transition of Metastable Wurtzite-Like CuInSe Nanocrystals.

Ternary I-III-VI semiconductors, such as CuInSe, exhibit diverse polymorphs with unique structural characteristics and optoelectronic properties. This study investigates the pressure-induced phase transitions of metastable wurtzite-like CuInSe nanocrystals. Using a combination of synchrotron X-ray diffraction, pair distribution function analysis, and density functional theory calculations, we reveal a transition from cation-ordered wurtzite-like (2) to cation-disordered NaCl-like (3̅) structures at 7.7 GPa. The cation-disordered NaCl-like phase persists upon decompression. Bulk modulus calculations highlight size-dependent deviations from bulk material behavior. These findings deepen our understanding of phase stability in colloidal I-III-VI semiconductor nanocrystals, with implications for tailoring functional materials under extreme conditions.