Excitation‐Dependent Emission Color Tuning of 0D Cs2InBr5·H2O at High Pressure

Abstract Self‐trapped exciton (STE) emission of low‐dimensional metal halides has witnessed explosive developments in both display and illumination, due to its intriguing photoluminescence properties. As one typical feature, STE emission energy is commonly independent of excitation wavelength. Herein, a rare phenomenon of inverse excitation‐dependent dual‐band emission is achieved on 0D Cs 2 InBr 5 ·H 2 O. Under initial compression, the contraction of inhomogeneously coordinated InBr 5 O octahedra gives rise to blue‐shifted STE emission with the decreased Stokes shift. As the phase transition occurs under higher pressure, considerable octahedral distortions generate a new defect‐related localized exciton emission. Notably, the high‐energy emission from the intrinsic STE state is only observed under the low‐energy excitation, which is believed to originate from the excitation‐dependent multiple excited states in high‐pressure Cs 2 InBr 5 ·H 2 O.