Bi ³⁺ and Sb ³⁺ Ions Regulate Photoluminescence of (NH ₄ ) ₂ ZrCl ₆ for White Light-Emitting Diodes and Information Encryption

Zero-dimensional zirconium (Zr)-based metal halide (NH4)2ZrCl6 microcrystals are successfully synthesized via a solvothermal method, and the regulatory mechanisms by which Bi3+ and Sb3+ doping modulates their photoluminescence (PL) properties are systematically probed. The structural characterizations confirming the efficient incorporation of dopant ions into the host lattice and temperature-dependent PL spectroscopy combined with time-resolved PL spectroscopy enabling the comprehensive investigation of self-trapped exciton dynamics and electron–phonon coupling effects in these doped systems. Specifically, Bi3+ achieves blue light emission through a strong electron–phonon coupling effect mediated by its 6s2 lone-pair electrons, whereas efficient orange-red light emission is attained by Sb3+ via self-trapped exciton emission. These distinctive photophysical properties not only facilitate the establishment of an excitation wavelength-dependent dynamic information encryption system but also enable the fabrication of white light-emitting diode (WLED) devices. The results of this work provide novel insights into the cation modulation and practical application of lead-free Zr-based metal halide PL materials.