A Polar Zinc-Based Water-Resistant White-Light Emission Organic Inorganic Hybrid Metal Halide

Developing lead-free hybrid metal halides with stable and efficient white-light emission remains a critical challenge for next-generation optoelectronics. Here, we report a polar zinc-based organic-inorganic hybrid halide, [EMPA]₂Zn₃Br₁₂ (EMPA = 5-[(4-ethylpiperazin-1-yl)methyl]pyridin-2-amine), which exhibits broadband white-light emission with a high color rendering index of 90 and high photoluminescence quantum yield of 43.9%. The material shows nonlinear optical properties with a measurable second-harmonic generation response. Unlike conventional hybrid halides, [EMPA]₂Zn₃Br₁₂ demonstrates exceptional stability, retaining its structure and luminescent properties after 60 days of immersion in water and prolonged exposure to UV irradiation. Temperature-dependent photoluminescence measurements reveal that the material maintains its white-light emission from room temperature down to 260 K. Density functional theory calculations suggest that the broadband emission originates from multiple self-trapped exciton states, facilitated by Jahn-Teller distortions in the [ZnBr₄]^2- tetrahedra. Furthermore, a white-light-emitting diode fabricated using [EMPA]₂Zn₃Br₁₂ as a single component white light emitter, demonstrating its potential for solid-state lighting. This study highlights [EMPA]₂Zn₃Br₁₂ as a promising lead-free alternative for environmentally friendly high-performance white-light-emitting and optoelectronic applications.