Yu Wang

Doping in single‐component metal halide perovskites to adjust defect levels plays a crucial role in self‐trapped exciton (STE) emission, which is critical for tunable multi‐mode luminescence and photochromism (PC). The introduction of cations (Pb ²⁺ ) into the hexagonal CsCdCl ₃ perovskite results in the disruption of the local symmetry of the matrix framework, establishing new trap states and trap centers, which in turn facilitate the creation of multimode persistent luminescence (PersL) materials. Temperature‐dependent fluorescence and thermoluminescence (TL) spectra reveal that Pb ²⁺ influences the redistribution of defects, providing new emission pathways and enabling efficient tuning of the room‐temperature emission. In addition, chlorine vacancies (V _Cl ) in CsCdCl ₃ :Pb facilitates the capture of electrons to form F‐centers, resulting in remarkable PC. First‐principles theory simulations demonstrate the introduction of Pb ²⁺ ions alter the original energy band structure and charge distribution, confirming their tendency to induce defect formation at different symmetry sites. This effective method of modifying the optical properties of CsCdCl ₃ microcrystals through Pb ²⁺ doping integrates multimode tunable UV/X‐ray induced PersL and rewritable PC, offering promising material candidates for more reliable and efficient anti‐counterfeiting and information storage applications.

With suitable electron-phonon coupling strength, a near-unity broadband photoluminescence quantum yield (PLQY) can be achieved in organic-inorganic hybrid metal halides (OIHMHs) via self-trapped exciton (STE) emission. However, it is still challenging to obtain high-quality red emission from OIHMHs with a desirable emission wavelength and high chemical stability, which hinders their practical application in high-performance displays, plant-growth lighting, and biomedical imaging. Herein, a series of hafnium-based zero-dimensional (TPP)₂HfCl₆·4C₂H₃N (TPP: tetraphenylphosphonium) single crystals with different Sb³⁺ doping levels are synthesized. The Sb³⁺-doped (TPP)₂HfCl₆·4C₂H₃N shows dual-band red emission with a full width at half-maximum of 178 nm and a high PLQY of 91.09%. This broad dual-band emission originates from dopant-induced extrinsic free excitons and STEs. Furthermore, (TPP)₂HfCl₆·4C₂H₃N:Sb³⁺ was employed as a luminescence converter in a light-emitting diode (LED) for plant growth regulation. A correlated color temperature of 4055 K and a color rendering index of 82.13 were achieved upon excitation of the LED at 365 nm. These results provide fundamental perspectives on the emission behavior of Sb³⁺-doped OIHMHs and illustrate their promise for use in plant-growth lighting.