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Scintillators, which can convert high‐energy particles (X‐rays) into detectable low‐energy ultraviolet–visible–near‐infrared photons, are essential components of X‐ray detectors and show extensive practical applications in nondestructive detection and medical imaging. Traditionally, inorganic scintillators represented by CsI:Tl have achieved definite progress. However, the harsh preparation conditions, high production cost, and poor mechanical properties impede their potential development in the high‐end X‐ray imaging field. Organic–inorganic hybrid metal complexes could be excellent alternatives, by virtue of their structural and spectral tunability, good solution processability, and excellent photophysical properties. This review mainly focuses on eco‐friendly lead‐free metal (Mn2+, Cu+, Sb3+, Sn2+, Ge2+, Ln3+, etc.) complex scintillators. The luminescence mechanisms are introduced and the scintillation performance, such as light yield, limit of detection, imaging resolution, etc., is highlighted. Moreover, the current challenges and perspectives in this emerging field are described. It is hoped to provide some theoretical guidance for the continuous development of the new scintillator systems. [ABSTRACT FROM AUTHOR]

X‐ray imaging technology has been widely used in the fields of environmental monitoring, safety inspection, nondestructive examination, space exploration, and medical diagnosis, among which scintillation materials play a vital role in indirectly converting X‐ray to visible photons. Here, a zero‐dimensional organic–inorganic hybrid halide C50H44P2SbCl5 crystal is prepared via a facile antisolvent precipitation method at room temperature. The single crystal of C50H44P2SbCl5 displays a strong yellow broadband emission centered at 592 nm with a near‐unity photoluminescence quantum yield of 98.42%. Importantly, C50H44P2SbCl5 crystals show great environmental stability and irradiation stability. Radioluminescence characterization indicates that C50H44P2SbCl5 crystals exhibit a good linear response to X‐ray dose rates along with an excellent light yield of 44 460 photons MeV−1, surpassing that of commercial inorganic LuAG:Ce scintillator. The spatial resolution of the C50H44P2SbCl5‐based scintillating screen is determined to be 8.2 lp mm−1. In conjunction with polymer thin film, the excellent scintillating feature of organic–inorganic hybrid halides offers exciting opportunities for achieving high‐quality flexible X‐ray imaging. [ABSTRACT FROM AUTHOR]

Scintillators have attracted tremendous attention due to their great potential in radiation detection, industrial non‐destructive testing, and medical theranostic applications. Thermally activated delayed fluorescence (TADF) based scintillators can simultaneously harvest radiation‐induced singlet and triplet excitons for high‐efficient X‐ray excited luminescence. However, pure organic TADF materials composed of light elements exhibit low X‐ray absorption coefficients, resulting in relatively weak X‐ray excited luminescence. Herein, a series of novel high‐performance X‐ray scintillators based on TADF mononuclear Cu(I)‐halide complexes are successfully developed. Together with high X‐ray absorption coefficient of heavy halogen elements and halide‐to‐ligand charge transfer characteristics, these TADF scintillators display excellent performance with high X‐ray relative light yields (as high as 28385 ± 1335 photons MeV−1), good linear response to X‐ray dose rate and high resistance to humidity and radiation. X‐ray imaging tests show that a relatively high spatial resolution of 9.8 lp/mm is realized based on their flexible scintillator films. These features suggest that it is a promising strategy to realize strong X‐ray excited luminescence by incorporating heavy halogen elements in TADF materials, providing more possibilities for exploring new low‐cost and high‐performance scintillators. [ABSTRACT FROM AUTHOR]

Developing scintillators with high light yield (LY), superior irradiation stability, and weak afterglow is of significance for the realization of low-dose high-resolution X-ray excited optical luminescence (XEOL) imaging. Lanthanide doped fluoride nanoparticles possess low toxicity, superior environmental stability, facial fabrication process, and tunable emissions, which are appropriate candidates for the next generation nanoscintillators (NSs). However, the low LY and strong positive hysteresis greatly restrict their practical application. Here, we propose an effective strategy that engineers energy gap to significantly enhance the LY. Our results verify that the tetragonal LiLuF4 host benefits the crystal level splitting of Tb3+ ions, which greatly promotes the electrons population on the Tb3+:5D4 level followed by the enhanced LY. The LY of LiLuF4:Tb@LiLuF4 NSs is calculated to be ∼ 31,169 photons/MeV, which is much higher than the lead halide perovskite colloidal CsPbBr3 (∼ 21,000 photons/MeV) and LuAG:Ce (∼ 22,000 photons/MeV) scintillators. Moreover, the positive hysteresis is remarkably restricted after coating a thin shell. The X-ray detection limit and spatial resolution are measured to be ∼ 21.27 nGy/s and ∼ 7.2 lp/mm, respectively. We further verify that this core/shell NS can be employed as scintillating screen to realize XEOL imaging under the low dose rate of 13.86 µGy/s. Our results provide an effective route to develop high performance NSs, which will promote great opportunities for the development of low-dose high-resolution XEOL imaging devices. [ABSTRACT FROM AUTHOR]

Nowadays, the development of X‐ray imaging has promoted the demand for new‐type scintillators, among which low‐toxic manganese(II) complexes have attracted burgeoning research interest. Herein, a highly stable manganese(II) complex with peculiar five‐coordinated modes is reported, which exhibits strong yellow emission peaked at 583 nm originating from d‐d transition of Mn2+ with high photoluminescence quantum yield (PLQY) up to 93%. The five‐coordinated manganese(II) complex has been rarely reported so far which is an innovative spot in the field of photofunctional metal complex. Thanks to the high PLQY and relatively large stokes shift, the manganese(II) complex yields bright yellow emission under low‐dose X‐ray irradiation and delivers excellent linear response to X‐ray, highlighting its suitability for X‐ray contrast imaging. Based on this, highly resolved X‐ray imaging is successfully achieved that can meet the requirements of many application scenarios. In addition, this manganese(II) complex demonstrates excellent radiation hardness, humidity resistance, and heat stability, indicating the application potential of scintillators in harsh environments. This research not only provides guidance for the design and fabrication of highly luminescent manganese(II)‐based complexes, but also demonstrates the potential of manganese(II)‐based complexes as scintillators for X‐ray imaging technology. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite quantum dots (QDs) CsPbX3 (X = Cl, Br, and I) have recently emerged as a new promising class of X‐ray scintillators. However, the instability of perovskite QDs and the strong optical scattering of the thick opaque QD scintillator film imped it to realize high‐quality and robust X‐ray image. Herein, the europium (Eu) doped CsPbBr3 QDs are in situ grown inside transparent amorphous matrix to form glass‐ceramic (GC) scintillator with glass phase serving as both matrix and encapsulation for the perovskite QD scintillators. The small amount of Eu dopant optimizes the crystallization of CsPbBr3 QDs and makes their distribution more uniform in the glass matrix, which can significantly reduce the light scattering and also enhance the photoluminescence emission of CsPbBr3 QDs. As a result, a remarkably high spatial resolution of 15.0 lp mm−1 is realized thanks to the reduced light scattering, which is so far a record resolution for perovskite scintillator based X‐ray imaging, and the scintillation stability is also significantly improved compared to the bare perovskite QD scintillators. Those results provide an effective platform particularly for the emerging perovskite nanocrystal scintillators to reduce light scattering and improve radiation hardness. [ABSTRACT FROM AUTHOR]

A novel Eu3+ ions-based metal–organic coordination polymer with a peculiar "snake-shaped" chain structure has been synthesized, which exhibits efficient light emission, excellent line response to X-rays and high structure and luminescence stability against continuous irradiation. [Display omitted] • A new type of luminescent Eu-MOCP was synthesized by simple solvothermal method. • Synthesized Eu-based MOCP shows an efficient and stable light emission under X-ray excitation, and delivers an excellent linear response to X-ray dose. • Compound 1 demonstrates high structure and luminescence stability against continuous X-ray irradiation. In this paper, a novel Eu ions-based metal–organic coordination polymer (MOCP) named Eu(1,3,6,8-PTS)(H 2 O) 7 ·4H 2 OHbipy (1) (PTS = pyrenetetrasulfonic acid) has been prepared, and its structure, stability, photoluminescence and scintillation properties were systematically investigated. Compound 1 gives a peculiar "snake-shaped" chain structure with the aid of π-π stacking effect of 4,4′-bipyridine auxiliary template. An efficient and stable light emission was detected under X-ray irradiation, which presents an excellent linear response to X-ray dose. Moreover, this compound demonstrates high radiation stability, illustrating its potential as a scintillator for X-ray detection. This work not only provides guidance for the design and fabrication of sulfonic ligand derived MOCPs with Eu (III) ions coordiantion, but also demonstrates the potential of MOCPs scintillators for X-ray detection technology. [ABSTRACT FROM AUTHOR]