Ultrafast Synthesis of a Highly Luminescent Zero-Dimensional Hybrid Perovskite TEA2HfCl6:Sb3+ for Optical Encryption and Healthy Lighting

Organic–inorganic hybrid metal halides have attracted considerable attention due to their facile synthesis, low cost, and high thermal and chemical stability. However, developing environmentally benign, readily synthesized, high-performance, and spectrally tunable broadband-emitting materials remains challenging. Herein, this study reports a zero-dimensional perovskite material, TEA2HfCl6:Sb3+, using a room-temperature coprecipitation method. This material exhibits low toxicity and excitation-wavelength-dependent modulation of singlet and triplet emission ratios, enabling broadband emission ranging from warm white to deep red. Notably, TEA2HfCl6:11%Sb3+ achieves a high photoluminescence quantum yield of up to 93.1%. Steady-state and time-resolved spectroscopic analyses reveal that these emissions arise from Sb3+-induced radiative transitions of singlet and triplet self-trapped excitons. Furthermore, leveraging its scalable synthesis process and favorable emission characteristics, the material shows potential for applications in large-area optical anticounterfeiting paper and full-spectrum, eye-friendly white-light-emitting diode (WLED). These findings highlight the dual functionality of TEA2HfCl6:Sb3+ in secure optical encryption and solid-state lighting, providing a promising platform for the development of multifunctional luminescent materials.