Search

The perovskite scintillators have been extensively studied recently for their merits of tunable emission spectra and simple preparation processes. However, the practical applications of perovskite scintillator-based X-ray image sensor are still impeded by inadequate radioluminescence, poor environmental stability, and low imaging resolution. Herein, we demonstrate a scalable co-firing method to fabricate high-quality lead-free Cs 3 Cu 2 I 5 perovskite scintillator and an Indium (In)-doping strategy is introduced to enhance its radioluminescence performance at the same time. The In-doped Cs 3 Cu 2 I 5 obtains a high PLQY of 77.9% and a relative light output of 53372 ph/MeV, which are 0.34 and 1.08 times higher than those of the undoped counterpart, respectively. The X-ray detection limit of the In:Cs 3 Cu 2 I 5 can reach 150.55 nGy air /s, 36.53 times lower than the requirement for X-ray medical diagnosis. The synthesized scintillator also shows superior stability under continuous high dose X-ray irradiation of 6800 μGy air /s for 120 minutes, maintaining 95% of its initial radioluminescence intensity. Furthermore, a large-area (300 cm2) flexible perovskite scintillator film is prepared, which owns a much competitive resolution of 10 lp/mm and less distortion in X-ray imaging. This work provides a practical path for the wide application of perovskite scintillator in the field of X-ray detection and imaging in near future. [Display omitted] • A co-firing method for lead-free indium doped Cs 3 Cu 2 I 5 perovskite scintillators has been proposed. • The indium doped Cs 3 Cu 2 I 5 shows superior environmental and radiation stability. • A large-area flexible scintillator film is prepared for high-resolution imaging. [ABSTRACT FROM AUTHOR]

Synergistic nanostructures possess enriched electrical and optical properties compared to conventional nanostructures. 1D - 3D synergized nanostructure was implied to elucidate the performance of the X-ray sensor for the first time. Current research in X-ray detection only focuses on implementing high attenuating material based on oxides/ perovskites in developing X-ray sensors. Herein we approached tailoring the performance of an X-ray sensor with a synergistic nanostructure composed of sodium vanadium oxide (NaV 3 O 8) with substantial grain boundary (GB) segregation of silver bismuth sulfide (AgBiS 2) , enabling the structured arrangement of nanostructured grains at the surface of NaV 3 O 8 nanorods. Then, it was coated as a thick film on top of the interdigitated electrodes by glass rod sliding technique to readout the dose-dependent X-ray sensing capability. From the X-ray impinged photocurrent characteristics, the sensor with 75 wt% AgBiS 2 segregated NaV 3 O 8 exhibits superior sensitivity 82.6 nC mGy−1 cm−2 and low-noise equivalent dose rate 1.04 mGy Hz−0.5 for 2.49 mGy s−1 than other compositions. These experimental findings explore the implication of synergistic nanostructures as active layers in direct conversion X-rays sensors for improved charge extraction and enhancement in X-ray impinged photocurrent at low dose rates. [Display omitted] • AgBiS 2 :NaV 3 O 8 segregated synergistic nanostructures with (100:0 wt%); (75:25 wt%); (50:50 wt%); (25:75 wt%) compositions was used to fabricate low-dose X-ray sensors. • X-ray impinged photocurrent characteristics reveal that X-ray sensors based on (25:75 wt%) NaV 3 O 8 : AgBiS 2 exhibit low dark current of 10-8A at 2 V bias condition. • Our device exhibit sensitivity of (82.6 nC mGy-1 cm-2) and NED (1.04 mGy Hz-0.5) at 2.49 mGy s-1 dose rate. [ABSTRACT FROM AUTHOR]

Nanocrystalline materials have garnered significant recognition in the scientific and research community for developing X-ray sensors. The applicability of bismuth-based binary and ternary compounds has been extensively studied in X-ray imaging and cancer therapy applications owing to their high attenuation. Among the binary and ternary compounds of bismuth, the n-type semiconductor silver bismuth sulfide (AgBiS 2) was studied for the detection of X-rays at lower doses, based on its total attenuation (μ = 3.07 cm2 g−1 at 70 keV), density (ρ = 7.02 g cm−3), and bandgap (E g = 1.21 eV). The effect of grain size on X-ray sensing performance was examined to validate the effective size required for maximum attenuation of X-rays and successful extraction of induced mobility carriers. X-ray sensors with four different AgBiS 2 grain sizes were cast on interdigitated electrodes (IDEs) and subjected to different doses of X-rays at 2 V bias to study its dose-dependent X-ray sensing nature using an intra-oral (70 kVp-AC) X-ray machine. AgBiS 2 -based X-ray sensor exhibited the highest sensitivity of 20.13 μC mGy−1 cm−3 with the lowest Noise-equivalent dose ratio (NED) of 0.08 μGy Hz−0.5, 0.20 mGy detection limit and a response time of 0.12 s. This outcome validates that AgBiS 2 can be applied as a potential replacement for perovskites in direct X-ray detection. [Display omitted] • Grain size effect on nano AgBiS 2 was studied for direct conversion X-ray detection at 70 keV X-ray photon energy. • As-prepared AgBiS 2 was heat treated at 150 °C for 15, 60, 90, and 180 min to study the grain size effect. • AgBiS 2 with 54 nm size exhibits superior sensitivity (20.13 μC mGy−1 cm−3), NED (5 μGy Hz−0.5) and swift response (0.12 s) for 7.97 mGy dose. [ABSTRACT FROM AUTHOR]

Semiconductor-based direct conversion X-ray sensors have widespread applications spanning from medical diagnosis to industrial inspection. However, current findings on X-ray detection based on perovskites shows high sensitivity but exhibit large leakage current and poor stability, thus, inhibiting them from commercialization. Highly stable AgBiS 2 with large attenuation coefficient (μ = 3.07 g cm−2 at 70 keV), shows excellent charge conversion due to its higher atomic number (Bi, Z = 83), and density (ρ = 7.02 g cm−3) was used for X-ray detection. Here, we approach to enhance the net sensitivity of AgBiS 2 by tailoring all three parameters by segregating micro/ nanocrystals of cerium oxide (CeO 2) at the AgBiS 2 grain boundary (GB) region. From the X-ray impinged photocurrent response, substantial GB segregation of n-CeO 2 at the AgBiS 2 interface leads to improved attenuation and promotes the conversion of multiple scattered X-ray photons into electrons by interacting with the adjacent grains, thus resulting in enhanced photocurrent generation. The sensitivity (S) and noise equivalent dose (NED) ratio were calculated to determine the lowest detectivity of the sensor with less generated noise signals. From these experimental findings, 10 % of n-CeO 2 segregation leads to an improvement in the sensitivity of AgBiS 2 to 29 μC mGy−1 cm−3. [Display omitted] • X-ray sensors were fabricated with micro/ nano CeO 2 segregated AgBiS 2 thick films. • Multiple scattered X-ray photons at the AgBiS 2 grain boundary region were effectively utilized by nano CeO 2 grains, resulting in higher charge carrier generation. • X-ray impinged photocurrent measurement revealed nano CeO 2 :AgBiS 2 presents record sensitivity 29.3 μC mGy−1 cm−3 for 7.97 mGy dose. [ABSTRACT FROM AUTHOR]

Bismuth-triiodide has received remarkable attention because of its properties like low toxicity, wide band gap, high density, high attenuation coefficient, and defect tolerance for direct X-ray detection applications. The material has demonstrated promising X-ray detection results in polycrystalline films and single-crystal detectors. However, the inherent defects and voids in the structure of BiI 3 create recombination centers and decrease the charge collection in the detector. Over the last few years, BiI 3 -polymer composites and BiI 3 -based perovskites have been investigated for the defect tolerance to deliver high sensitivity, high SNR, and low detection limit. These composites and perovskites tailor the trap density in the BiI 3 and increase the density of shallow defects, which helps to improve the charge collection. In this review, we summarize the properties and limitations of BiI 3 and the role of deep and shallow defects in charge carriers' transportation. The highlights of the recent developments in BiI 3 -based composites and perovskites to address these challenges to yield high material performance for direct X-ray detection applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] A diode was designed in the shape of a silicon cube with p–n junctions on all sides. [•] The purpose was to create an X-ray detector with angular independent response. [•] The cubes were manufactured with a micromachining process. [•] The angular variation in the response was reduced with a factor 7. [ABSTRACT FROM AUTHOR]

• The 25 µm-thick ZnO film using sputtering method was characterized for X-ray detection applications. • p+-Si/ZnO X-ray detector based on the 25 µm-thick ZnO film shows a high sensitivity of 128 μC∙Gy−1∙cm−2 at − 20 V. • The on-off response is related to the V O defect, which was verified by the transmittance spectrum and the TSC spectrum. [Display omitted] In the field of direct-conversion flat panel X-ray detector, semiconductor with thickness of tens to hundreds microns is needed. In this paper, we demonstrate that thick ZnO semiconductor deposited by RF magnetron sputtering can be candidate for the X-ray detector. The 25 µm ZnO film was prepared by sputtering method under 200 °C and a p+-Si/ZnO X-ray detector based on the thick ZnO film was investigated to explore its X-ray detection properties. The detector shows nonzero short circuit current and open circuit voltage indicating the heterojunction nature of the ZnO film in contact with the p+-Si substrate. The detector shows linear response to the X-ray dose rate and has a high sensitivity of 128 μC∙Gy−1∙cm−2 at −20 V under 30 kV p X-rays indicating its great potential in the flat panel X-ray detector applications. The on-off response of the detector is related to the V O defect in the ZnO film, which can be verified from the transmission spectrum, the thermal stimulated current spectrum, and the photoluminescence spectrum. [ABSTRACT FROM AUTHOR]

• Novel crushed perovskite crystal/polymer composite films were prepared by mechanical grinding and sieving processes. • X-ray detectors based on the perovskite/polymer composite films demonstrated excellent stability, low dark current and noise and fast response. • The as-prepared devices exhibited high X-ray sensitivity of ∼488 μC/(Gy air cm2) with lowest detectable X-ray dose rate of 2.3 μGy air /s. Organic-inorganic hybrid perovskite materials have attracted increasing attention in recent years for ionizing radiation detection due to their large cross-section for high energy X-ray or gamma ray, defect-tolerance, large mobility lifetime product, tunable bandgap and facile preparation of single crystals. However, the thickness of solution processed perovskite polycrystalline films are normally limited, and single crystals are fragile and hard to be utilized as a device. In this article, we successfully realized the preparation of the perovskite crystal/polymer composites, through a novel process involving mechanically grinding and sieving. X-ray detectors were fabricated based on the relatively thick composite films via solution process. The device performance under the irradiation of X-rays were also investigated, in terms of stability, dark current, noise and temporal response. Our devices exhibited remarkable performance metrics, which proved that the perovskite composite films can be used to fabricate highly efficient and low-cost X-ray detectors. [ABSTRACT FROM AUTHOR]