Doped Emitting Cesium Silver Halides as X‐Ray Scintillator with Fast Response Time, High Absorption Coefficient, and Light Yield

Abstract

Radioluminescence materials (scintillators) are widely investigated because of their potential application in many fields, such as medical imaging, security‐related techniques, and nondestructive inspection. However, the fabrication of scintillator materials with simultaneously fast response time, high absorption coefficient, and high light yield, as well as low toxicity is still a challenge. Herein, the synthesis of Cu(I)‐doped Cs2AgI3 single crystals (SCs) with a 1D crystal structure is presented. A bright blue‐green photoluminescence (PL) is observed after incorporating Cu+ into the Cs2AgI3 SCs under UV irradiation at room temperature. The PL quantum yield of the doped samples can reach up to 73% at a Cu+ concentration of 0.66%. Experimental and theoretical studies show that the blue‐green emission may originate from self‐trapped excitons, which is further verified by photophysical results from control experiments on pure Cs2AgI3 SCs. Upon X‐ray excitation, Cu‐doped SCs exhibit fast scintillation decay time (288 ns), high light yield (27 000 photons per MeV), and high absorption coefficient compared with the commercial product (CsI: Tl). These results suggest that Cu‐doped Cs2AgI3 is an ideal scintillator, which will be a promising candidate for potential application in dynamic real‐time imaging and radiation detection.

High-Performance Copper-Doped Perovskite-Related Silver Halide X-ray Imaging Scintillator

“…Because of the great flexibility of pure PDMS, the C-CAI@P film can recover from any mechanical deformation, such as folding, stretching, poking, or twisting (Figure S13), implying its great potential for imaging nonplanar objects. Surprisingly, the C-CAI@P film showed a higher PLQY of 72.6% compared with 5% doped C-CAI powders, approaching that of C-CAI single crystals . Moreover, tracking the PLQY of the C-CAI@P films for 45 days demonstrated the films’ improved environmental stability, with only a 3.5% reduction in PLQY value compared to the 5% decrease observed for C-CAI powders (Figure S14).…”

“…In addition, the long carrier decay time of copper halide scintillators (i.e., on the order of microseconds) also restricts their real-time detection capability. , Since the ability to attenuate X-rays is mainly determined by the effective atomic number of a material, lead-free silver halides, which possess a higher atomic number and exhibit a shorter decay time than copper halides, could be exploited as excellent alternatives . Several polycrystalline silver halide powders and single crystals with tunable emission have been synthesized recently, albeit through expensive solid-state techniques. , Unfortunately, polycrystalline powders have exhibited extra Cs-related peaks in their X-ray diffraction patterns, implying poor phase purity. Moreover, Cu-doped silver halide single crystals have demonstrated an unsatisfactory light yield of ∼27 000 photons/MeV, which lags far behind the yield of the commercial X-ray scintillators mentioned above .…”

“…Several polycrystalline silver halide powders and single crystals with tunable emission have been synthesized recently, albeit through expensive solid-state techniques. , Unfortunately, polycrystalline powders have exhibited extra Cs-related peaks in their X-ray diffraction patterns, implying poor phase purity. Moreover, Cu-doped silver halide single crystals have demonstrated an unsatisfactory light yield of ∼27 000 photons/MeV, which lags far behind the yield of the commercial X-ray scintillators mentioned above . Furthermore, the detection limit and X-ray imaging ability of Cu-doped silver halide scintillators have not been characterized.…”

“…As shown in Figure S9, double-emission peaks can be observed from 80 to 160 K, where the positions of the peaks are 405 and 470 nm, respectively, corresponding to the emission of the intrinsic CAI powders and the emission enhanced by the inclusion of dopant atoms (Figure S10). The emission peak at 405 nm clearly dominates the spectra between 80 to 160 K, and its intensity decreases with increasing temperature until it completely disappears due to thermal quenching. Based on all of these results, the luminescence mechanism of the synthesized C-CAI powders is speculated to be, as illustrated in Figure e, with the sky-blue emission originating from the second self-trapped state.…”

Colloidal Cu4I4 Clusters for High-Resolution X-ray Imaging Scintillation Screens

“…Zhang et al reported a large-area (72 cm 2 ) scintillation screen that was formed by the self-assembly of CsPbBr 3 nanosheets . However, serious problems such as significant self-absorption effect, lead toxicity, and poor environmental stability have limited the commercialization of these perovskite materials. ,, Recently, a class of lead-free perovskite-related metal halides based on copper, silver, and manganese have been found to exhibit excellent scintillation properties due to their exceptional optical properties and negligible reabsorption as well as high PLQY. − More specifically, the Cs 3 Cu 2 I 5 and Cu-doped Cs 2 AgI 3 scintillation screens achieved high light yields of ∼48800 and ∼82900 photons MeV –1 and ultralow detection limits of 48.6 and 77.8 nGy s –1 , respectively. , Unfortunately, the original metal halides exhibited poor humidity stability due to the high solubility of CsI in water. , Additionally, the further improvement of X-ray imaging spatial resolution was hindered by the conventional process, which is to directly mix metal halide powders and a polymer matrix. ,, Although achieving light-guiding properties with high transparency is beneficial for improving the resolution of ceramic scintillators, the complicated fabrication process with relatively high temperatures and pressures as well as high cost is still needed. , While the ideal spatial resolution can be achieved with the assistance of anodized aluminum oxide (AAO) template because of its well-defined porous structure and the small refractive index, the ineluctable X-ray absorption, fragile body-self, and ungovernable thickness of the AAO template are inevitable drawbacks. − …”