High-PressurePhase Transition of Metastable Wurtzite-LikeCuInSe₂ Nanocrystals

Ternary I–III–VI₂ semiconductors, such as CuInSe₂, exhibit diverse polymorphs with unique structural characteristics and optoelectronic properties. This study investigates the pressure-induced phase transitions of metastable wurtzite-like CuInSe₂ 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 (<i>Pmc</i>2₁) to cation-disordered NaCl-like (<i>Fm</i>3̅<i>m</i>) 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–VI₂ semiconductor nanocrystals, with implications for tailoring functional materials under extreme conditions.