Ultrafast dual-pathway room-temperature synthesis of 0D inorganic metal halides K3SbCl6 with near-unity photoluminescence quantum yield

Abstract

Alkali metal halides (such as KCl) as typical insulators, suffer from poor luminescence due to their intrinsic broad bandgaps. Although ion doping can enhance the luminescence properties of these compounds, the mechanism of foreign ions that undergo ultrafast diffusion into the host lattice or construct new compounds remains an open question. In this study, Sb³⁺ was doped into a KCl matrix via room-temperature grinding route. By varying the Sb³⁺ concentration, a structural evolution from KCl:Sb³⁺ to the 0D inorganic metal halides (IMHs) K₃SbCl₆ has been confirmed. The resulting K₃SbCl₆ exhibits broad-spectrum yellow emission with near-unity photoluminescence quantum yield. The luminescence mechanism can be attributed to the ³P₁→¹S₀ transition of Sb³⁺ ions, characterized by a broad emission band. Furthermore, a room-temperature solid-liquid interface diffusion method is developed for ultrafast single-crystal growth of K₃SbCl₆ (only 20 s) with stable luminescence, and demonstrated excellent temperature sensing performance within the 50–310 K range, achieving a maximum relative sensitivity of 9.99%/K. Additionally, the application potential of K₃SbCl₆ is successfully demonstrated in information encryption, flexible composite fluorescent films, and white light-emitting diodes. This study provides new insights and prospects for the ultra-fast synthesis of high-performance luminescent materials.