Excited‐State Pathway Switching via Reversible Structural Phase Transitions in Sb ³⁺ ‐Doped Cadmium Halides

STE states. This contrast originates from the different Cd-Cl coordination environments (octahedral vs. tetrahedral), which modulate the energy levels and transition dipole moments. Importantly, hydrochloric acid (HCl) and 4,4-difluoropiperidine induce fully reversible interconversion between the two structures, allowing dynamic switching between yellow and deep-orange emission. Based on this reversible luminescence, we further demonstrated applications in dynamic anti-counterfeiting and multilevel information encryption. This work establishes a coordination-structure-driven strategy for programmable emission in 0D hybrid metal halides.