Mn²⁺ and Sb³⁺ Codoped Cs₂ZnCl₄ Metal Halide with Excitation-Wavelength-Dependent Emission for Fluorescence Anticounterfeiting

Abstract

In recent years, there has been a growing demand for luminescence anticounterfeiting materials that possess the properties of environmentally friendly, single-component, and multimode fluorescence. Among the materials explored, the low dimensional metal halides have gained wide attention because of unique characteristics including low toxicity, simple synthesis, good stability, and so on. Here, we synthesized Mn2+ and Sb3+ codoped Cs2ZnCl4 single crystals by a facile hydrothermal method. Under 365 nm excitation, the codoped compound exhibits dual-band emissions at 530 and 730 nm. However, under 316 nm excitation, the compound only shows one emission band from 500 to 850 nm peaking at 730 nm, while under 460 nm excitation, the emission from 500 to 650 nm with an emission peak at 530 nm can be observed. Based on the study of the photoluminescence mechanism, the green and red emissions originate from the Mn2+ located in the tetrahedron and self-trapped exciton emission of [SbCl4]− clusters, respectively. Due to the zero-dimensional structure of the Cs2ZnCl4 host, there is minimal energy transfer between these dopants. Consequently, the luminous ratios of the two emissions can be independently regulated. Except by tuning the dopant concentrations, the Cs2ZnCl4:Mn2+, Sb3+ demonstrates excitation-wavelength-dependent properties, which could emit more than two colors with the change of excitation wavelength. As a result, multimode anticounterfeiting based on Cs2ZnCl4:Mn2+, Sb3+ crystals has been designed, which aligns with the requirements of environmentally friendly, single-component, and multimode fluorescence properties.

Realizing efficient photoluminescence spectral modulation via Sb3+/Ln3+ co-doping in Cs2NaInCl6 double perovskites

“…23,30,31 Cs 2 NaInCl 6 is a promising material that can be used in light-emitting applications due to its direct bandgap nature, but the parity-forbidden transition restriction makes undoped Cs 2 NaInCl 6 usually exhibit low PLQY. 17,21,32 Therefore, we used Sb 3+ -doped Cs 2 NaInCl 6 as the host and investigated the optical properties of Cs 2 NaIn 1− x Sb x Cl 6 crystals with different contents of Sb 3+ ions using steady-state PL and TRPL spectral measurements. As shown in Fig.…”

“…Ion doping has been proven to be an effective way to modulate the energy band structure and improve the optical properties of lead-free halide double perovskites. 16,18–22 For example, Zheng et al reported a dramatically improved PLQY of Cs 2 AgInCl 6 with co-doping of Bi 3+ and Na + ions. The introduction of the Bi 3+ ion can break the parity-forbidden transition and convert dark STEs into bright phosphors.…”

Band gap engineering and photoluminescence tuning in halide double perovskites

“…Additionally, time-resolved PL showed a single exponential decay behavior for both Mn 2+ and Sb 3+ emission. 77 Energy transfer between the dopants was observed for the Cs 2 NaInC l6 :RE 3+ ,Sb 3+ HDP. 78 Cs 2 NaInC l6 :Er 3+ ,Sb 3+ emits light in quite separated regions of the spectra – blue and near infrared.…”