Scintillators are widely used for radiation detection in various fields, such as medical imaging, nondestructive testing, and crystallography. X-ray-generating systems typically emit large amounts of heat and require a high thermal stability of scintillators, particularly for nondestructive testing or radiation detection performed under harsh conditions. Therefore, highly stable scintillators must be developed for application in extreme environments. Herein, we developed new zero-dimensional lead-free monoclinic phases of Cs 3 TbCl 6 and Rb 3 TbCl 6 metal halides that are thermally and chemically stable. Cs 3 TbCl 6 and Rb 3 TbCl 6 polycrystals exhibit high light yields of 56800 and 88800 photons/MeV, respectively. Cs 3 TbCl 6 and Rb 3 TbCl 6 polycrystals also show low detection limits of 149.65 and 115.38 nGyairs −1 due to their structural−optical properties, respectively. Furthermore, the fabricated thick films of Cs 3 TbCl 6 and Rb 3 TbCl 6 are applied to our homemade X-ray imaging system, and preferable spatial resolutions are obtained as compared with a commercial Gd 2 O 2 S:Tb 3+ film.S cintillators that convert high-energy photons (such as Xrays) to low-energy visible photons have become crucial for a wide range of applications, including medical diagnostic imaging, nondestructive testing, crystallography, quality inspection, security, etc. Materials such as CsI (CsI:TI), LYSO (Lu,Y) 2 SiO 5 :Ce 3+ ), and GOS (Gd 2 O 2 S:Tb 3+ ) are currently widely used as scintillators in indirect X-ray detectors. 1−4 However, they have several limitations such as complicated synthesis processes and poor thermal stability. 5−7 Recently, lead halide perovskites (LHPs) have attracted significant attention as scintillators due to their low detection limits and the possibility of multicolor radioluminescence (RL). 8−12 However, the main drawbacks of the LHPs as scintillators are low thermal and chemical stability and selfabsorption properties of LHPs. Moreover, the inherent toxicity of lead is a critical limitation of LHPs. 13−16 Recently, lead-free metal halides have been developed as scintillators. 17,18 For instance, Yang et al. reported that Rb 2 CuBr 3 was as a scintillator with a high light yield 19 and Zhang et al. applied Rb 2 AgBr 3 , with its short scintillation decay time, to dynamic Xray imaging. 20 In addition, Jiang et al. applied C 4 H 12 NMnCl 3 and (C 8 H 20 N) 2 MnBr 4 for a WLED and X-ray scintillator. 21 Recently, Tb 3+ -doped metal halides have attracted attention due to their interesting luminescence properties. Liu et al. reported persistent radioluminescence and excellent X-ray imaging using NaLuF 4 :Tb 3+ . 22,23 However, despite these excellent findings, no studies have been able to overcome the

White‐light‐emitting single‐component materials are in high demand for lighting applications. However, achieving white light in single‐doped metal halide materials remains a challenge. Herein, for the first time, zero‐dimensional Cs3ScCl6:Sb3+(CSC:Sb3+) nanocrystals (NCs) are reported that exhibit bright white‐light emission, which is a result of combination of the excessive blue and yellow emissions of carbon dots and spin‐forbidden electronic transitions of Sb3+ ions. CSC:Sb3+ NCs exhibit a high photoluminescence quantum yield of 48%. Furthermore, they retain 75% of their original photoluminescence efficiency at 100 °C. This high thermal stability is mainly attributed to its lower dimensionality and high exciton binding energy as they facilitate the creation of stable white light at elevated temperatures. A single‐component white‐light‐emitting diode fabricated using CSC:Sb3+ NCs exhibits a high‐color rendering index and luminous efficacy values of 90 and 23 lm W−1 at a high flux current of 200 mA. Therefore, the findings may pave the way for developing the next generation of white‐light‐emitting devices using a single component of white‐light‐emitting material.

No abstract