Search

Two-dimensional (2D) perovskite single crystals have risen to be prominent in the domain of optoelectronic materials due to their exceptional characteristics including notably low ion migration and defect density. A distinguishing feature is the strategic inclusion of larger organic amine spacer, alternately inserted between inorganic lead halide octahedral layers. This spacer effectively mitigates ion migration, even under higher bias voltages, which is particularly advantageous for X-ray detection. However, the simultaneous realization of multiple functions within this realm remains a formidable challenge. In this work, we have synthesized a high-quality organic spacer-incorporated single layered 2D perovskite single crystal of [CYP]PbBr 4 (CYP = 1-cyclohexylpiperazine). Our findings reveal the impressive potential of [CYP]PbBr 4 in the domain of X-ray detection, as evidenced by the ultrahigh X-ray sensitivity, long-term stability, and astonishingly low detection limit of 1.72 nGy air s-1. Notably, [CYP]PbBr 4 also emits bright broadband yellow light with quantum yield of 30.3%, and the fabricated white LED achieves a high Color Rendering Index of 94.1, which surpasses that of commercially available white LED based on YAG: Ce3+ (< 80). [Display omitted] • [CYP]PbBr 4 shows the spectral-selective photoconductivity, specifically, it is sensitive to UV-light illumination below about 400 nm but almost blind to the standard visible light (above 400 nm), showcasing the potential in visible-blind ultraviolet photodetection. • The X-ray photoconductor device, featuring an Au- [CYP]PbBr 4 -Au structure, has demonstrated outstanding sensitivity and minimal detection limit of 1.72 nGy air s-1 and exhibites enduring stability toward X-ray over 1500 min without additional protective shell. • This compound display bright broadband yellow light emissionwith moderate photoluminescence quantum yield of 30.3%. Most notably, the fabricated white LED achieves an extraordinary Color Rendering Index (CRI) of 94.1. • We believe our findings will provide valuable insights into the rationa design of new 2D organic-inorganic hybrid halides for advanced X-ray detection and solid-state lighting applications. [ABSTRACT FROM AUTHOR]

This study investigated the use of inorganic cadmium selenide nanoplatelets (CdSe NPLs) to enhance the performance of X-ray detectors. The active layer of the detector comprised a bulk heterojunction composed of PCDTBT:PC 71 BM: CdSe NPLs with three different aspect ratios (ARs = 3:1, 1:1, and 6:1). The CdSe NPLs, synthesized with a thickness of five monolayers, were controlled by adjusting the molar mass ratios of Cd(OAc) 2 and Cd(OAc) 2 ∙2 H 2 O. Each detector was characterized by analyzing its series resistance, collection irradiation, dark current density, detection sensitivity, charge mobility, and defect density via the collected charges. The detector containing CdSe NPLs with an aspect ratio of 1:1 demonstrated the most favorable performance, exhibiting improved carrier generation and transport properties, resulting in a 23.36 % increase in sensitivity compared with the detector without CdSe NPLs. Through experimentation, the optimal content of CdSe NPLs in the active layer was determined to be 1 wt%, yielding the highest sensitivity of 3.96 × 103 μC∙Gy−1∙cm−2. This study underscores the potential of CdSe NPLs as promising materials for X-ray detector applications. • Utilized CdSe nanoplatelets (NPLs) to enhance X-ray detector performance. • Demonstrated 23.36 % sensitivity increase with optimized CdSe NPLs (AR = 1:1). • Revealed CdSe NPLs altered surface morphology, enhancing light absorption. • Highlighted potential of CdSe NPLs for improving various optoelectronic devices. [ABSTRACT FROM AUTHOR]

Perovskite X-ray detectors are actively investigated because of their exceptional properties, including their significant attenuation coefficient, low defect density, excellent transport characteristics, easy growth, and high sensitivity to X-ray photons. However, perovskite-based high-energy X-ray detectors on the MeV scale are rarely explored. In this study, we investigate the optoelectronic characteristics and radiation detection capabilities of triple-cation Cs 0.05 FA 0.9 MA 0.05 PbI 3 single crystals (CSC) grown using the inverse temperature crystallization method. The CSCs with a reduced Goldschmidt tolerance factor owing to the presence of Cs and MA ions exhibit exceptional properties, including a bandgap of 1.447 eV, low dark current, and self-powered response to X-ray irradiation. The X-ray absorption rate of 36 keV exceeded 99% with a CSC thickness of 2 mm, demonstrating its strong stopping power. Moreover, the CSC detectors exhibit precise linear responses to varying X-ray doses and dose rates with R2 values close to 1 and relative standard deviation (RSD) values below 3% under all the tested conditions. In addition, the detector effectively detected high-energy X-rays of up to 15 MV with minimal variations in the RSD values. These findings highlight the potential of CSC as promising materials for high-performance X-ray detectors. • Triple-cation lead–halide perovskites for high-energy X-ray detection were studied. • CSC detector has uniform linear response to varying X-ray doses and rates. • CSC detector can detect high-energy X-rays of up to 15 MeV. • CSC demonstrated remarkable promise as excellent self-powered X-ray detectors. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) hybrid perovskite single crystals are promising photovoltaic materials. However, the single crystals grown from solution usually respond poorly to light and other charged particles. The 2D (BDA)CsPb 2 Br 7 single crystals (BDA = 1,4-butanediamine) are grown from a supersaturated solution. The macroscopical growth steps are present on the surface, leading to a large leakage current during device operation. The surface defects are removed to expose a clean and flat surface. This well-defined crystallographic surface enables an Ohmic contact with the electrode, which minimized the dark current and baseline drift. Consequently, the assembled devices exhibit an enhanced response to LED light and X-rays, revealing the surface defect to be one of the culprits underneath the poor performance of solution-grown perovskite single crystals. • The (BDA)CsPb 2 Br 7 perovskite single crystal was grown by solution cooling method. • Surface defects worsen the detection performance of crystals for photons and X-rays. • A surface treatment method was used to remove defects and improve device performance. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have gained significant attention as promising materials for ionizing radiation detection due to their facile fabrication process, exceptional optoelectronic properties and high attenuation coefficients. To effectively absorb the incident X-ray photons, thick active layers have been reported and fabricated via spray-coating. However, the conventional spray-coating method is susceptible to various adverse effects, making it challenging to achieve high-quality thick perovskite films. In this work, we propose the use of antisolvent-assisted spray-coating to deposit perovskite films, which results in small surface roughness, thick films on various substrates. The slow growth of the thick film and the ability to regulate its crystallization through the modulation of processing atmosphere were also carefully studied. The optimized X-ray detector demonstrated a sensitivity of up to 3370.8 μC Gy air −1 cm−2, demonstrating its great potential for X-ray detection applications. • Anti-solvent spray-coating technique was established to deposit perovskite thick films. • The spray-coating process was systematically investigated and optimized. • Optimized devices based on antisolvent-assisted X-ray detectors are promising for real applications. [ABSTRACT FROM AUTHOR]

The rising requirement for radiation detection materials for practical applications has inspired to burgeoning investigation of scintillator materials. High performance X-ray detection require high spatial resolution and long-term stability, particularly for targeted objects at extreme conditions. Here, the CaF 2 :Eu2+ glass ceramic (GC), in which the CaF 2 :Eu2+ nanoparticles are wrapped by the glassy matrix, is successfully obtained the melting method. The as-obtained CaF 2 :Eu2+ GC manifests bright blue radioluminescence (RL) emission peaked at 470 nm thanks to the effective 5d-4f transition of Eu2+ ions. In addition, the as-obtained CaF 2 :Eu2+ GC presents high transmittance of 84.2% and visible light, contributing an excellent spatial resolution of 15 lp/mm at room temperature. Importantly, the as-obtained CaF 2 :Eu2+ GC exhibits high robustness at water conditions and high thermal stability with X-ray resolution of 12.1 lp/mm at 473 K. Our work demonstrates that CaF 2 :Eu2+ GC scintillators provide an excellent visualization tool for high-resolution scintillators X-ray images in harsh conditions. • The reduction efficiency of Eu2+ is significantly improved by mixing the reducing agent with glass ceramic raw and sintering. • The CaF 2 :Eu2+ glass ceramic is successfully obtained by melt-quenching method. • Multiple characterization prove that Eu2+, the luminescent center of glass ceramic, is greatly reduced in glass ceramic. • The strategy significantly reduces the light scattering and enhance the stability of the emitting centers. • The CaF 2 :Eu2+ glass ceramic for high resolution X-ray detection in harsh conditions. [ABSTRACT FROM AUTHOR]

X-ray detectors have drawn great attention due to their wide applications in medical imaging and industrial inspection. Lead halide perovskite exhibits excellent X-ray detection merits because of its high-Z element and outstanding photoelectric properties. However, the perovskite-based X-ray detectors exhibit poor stability, low resistivity and large dark leakage current due to the soft lattice and ion migration of perovskite materials. Herein, we used Ga 2 O 3 compact layer to form a heterojunction structure with formamidinum lead iodide (FAPbI 3) to largely ease these issues. Compared with the bare FAPbI 3 detector, the dark current of the FAPbI 3 /Ga 2 O 3 heterojunction detector is reduced by 3 orders of magnitude and the photo-to-dark current ratio (PDCR) increased by 31-fold. The detection limit of 0.23 mGys−1 is obtained which is 20 times lower than the FAPbI 3 detector and short response time of 20 ms is obtained. More importantly, the FAPbI 3 /Ga 2 O 3 device exhibits better repeatability due to the suppression of ion migration by Ga 2 O 3. This work provides an effective strategy to obtain low dark current and stable perovskite-based photodetector. • A coplanar interdigital MSM-structured X-ray detector was fabricated based on FAPbI 3 /Ga 2 O 3 heterojunction. • Low dark current density (4.1 pAmm−2), high PDCR (433) and low detection limit (0.23 mGys−1) were obtained. • The performance improvement of the device is due to the suppression of iodine ions migration by compact Ga 2 O 3. [ABSTRACT FROM AUTHOR]

Metal halide perovskites nanoparticles (PNPs) show promising application in X-ray detection and imaging. However, they exhibit poor stability, especially, the emission peak might be evidently shifted with increasing the PNPs concentration. In this work, the composites of CsPbBr 3 PNPs and BaLuF 5 : 15Gd/15Tb NPs are used to prepare scintillation film for the first time. When fixing the PNPs content in the film, its emission center is not changed after the addition of fluoride NPs. The uniform film containing both BaLuF 5 : 15Gd/15Tb to CsPbBr 3 is prepared. The scintillation intensity of the CsPbBr 3 PNPs is enhanced owing to the radiative energy transfer process from BaLuF 5 : 15Gd/15Tb to CsPbBr 3. Our results provide a novel route to improve the scintillation intensity, which might promote the exploration of new scintillators with high performance. • The composite of CsPbBr 3 and BaLuF 5 : Gd/Tb is used to prepare scintillation film. • The PL profile of CsPbBr 3 is not changed after the addition of fluoride NPs. • The RL intensity of CsPbBr 3 is enhanced owing to the radiative energy transfer. • The RL intensity of mixture is increased by ∼ 2.3 times compared to CsPbBr 3. [ABSTRACT FROM AUTHOR]

• PL, XEL and sensing properties of Er3+ and Er3+/Yb3+ doped Gd 2 Zr 2 O 7 are studied. • A good radiation resistance is realized for these samples with pyrochlore structure. • Er3+ emissions keep stable under continuous X-ray excitation. • FIR of 2H 11/2 to 4S 3/2 is insensitive to excitation powers with S r-max of 1.1% K−1. • Er3+/Yb3+: Gd 2 Zr 2 O 7 can be used for optical thermometry and X-ray detection. A series of Er3+-doped and Er3+-Yb3+ co-doped Gd 2 Zr 2 O 7 phosphors were synthesized via hydrothermal method, and their multifunctional properties were studied in detail. The Raman spectra indicated that the products were the ordered pyrochlore phase of Gd 2 Zr 2 O 7 , which exhibited a good radiation resistance. The up-conversion (UC), down-conversion (DC) photoluminescence (PL) and X-ray excited luminescence (XEL) spectra of the Er3+: Gd 2 Zr 2 O 7 samples showed the similar spectra profiles, which were composed of the prominent green (2H 11/2 /4S 3/2 →4I 15/2) and weak red (4F 9/2 →4I 15/2) emissions. The co-doping of Yb3+ ions was beneficial for the improvement in UC PL but led to the reductions in DC PL and XEL. Besides, the X-ray induced green emissions demonstrated a high-sensitivity to the dose rate and a long-term stability against the continuous X-ray irradiation. Moreover, using the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors were analyzed based on the thermally coupled levels (TCLs) 2H 11/2 and 4S 3/2 of Er3+. The FIRs were found to be insensitive to the excitation power variation, and the optimal relative sensing sensitivity reached ~1.1%K−1 at 298 K. These characteristics may enable the studied system applicable for optical thermometry, X-ray detection and X-ray imaging. [ABSTRACT FROM AUTHOR]

Nanoparticulate powders of Eu-doped Lu2O3 were prepared using combustion process and glycine as a fuel. Such powders could be relatively easily sintered to translucent bodies at 1700 °C. Excitation and emission spectra were recorded for both types of the materials. The excitation spectra revealed the existence of much more efficient energy transfer from the host to the dopant in the sintered ceramics. Strong variations in the relative intensities of the excitation transitions are seen when comparing the powder and its sintered analog. This was explained assuming preferential occupation of the C3i site in the glycine-derived powder in comparison with the pellets. Most profound emission under X-ray excitation was found for the sintered ceramic doped with 5% of Eu. [Copyright &y& Elsevier]

• Glasses in the system NaPO 3 -Ba(PO 3) 2 -MgF 2 -YF 3 doped with EuF 3 (x = 0.0-4.0 mol%) or Dy 2 O 3 (x = 0.0-1.0 mol%) were investigated as high energy sensors. • The glasses present excellent optical quality up to the dispersion level of 4.0 mol% Eu3+ and at least up to 1.0 mol% Dy3+. • No sign of photoluminescence or radioluminescence intensity saturation was observed for the highest RE activator concentration suggesting that higher RE activator concentrations could lead to still higher luminous output. • Photoluminescence spectra measured under varying excitation powers at 365 nm allow construction of calibration curves that can be used to quantitatively detect the UV radiation. • Luminescence and excited state lifetime values indicate the glasses are promising candidates for glass scintillators for X-ray detection. In this work, fluorophosphate glass samples with the composition 35NaPO 3 -30Ba(PO 3) 2 -25MgF 2 -(10- x)YF 3 –x[EuF 3 or Dy 2 O 3 ] with x = 0–4.0 mol% EuF 3 , or x = 0–1.0 mol% Dy 2 O 3 , were fabricated by the melt quenching technique. The glasses were characterized from the structural, thermal and optical-spectroscopic points of view. Emission spectra were measured in the visible range upon UV excitation. Luminescence decay curves were registered by monitoring the most intense emissions of Eu3+ (5D 0 →7F 2) and of Dy3+ (4F 9/2 →6H 13/2) in the red and green, respectively, and from them the average lifetime values of the excited states 5D 0 of Eu3+ (2.5 ms) and 4F 9/2 of Dy3+ (0.71 ms) were determined. Emission spectra measured under variable excitation power yielded calibration curves for Eu3+ and Dy3+-doped glasses. The response to X-ray excitation was evaluated through radioluminescence measurements. The results indicate the promising application of these glasses in scintillators and for X-ray sensing devices. [ABSTRACT FROM AUTHOR]

Due to the high density of lithium storage and abundant mineral resources, silicon has been well accepted as a promising anode for the new-generation lithium-ion batteries. In recent years, its poor cycle stability due to drastically volumetric change has been remarkably improved by means of such composites as Si–Cu or Si–Cu 3 Si. However, the preparation is still complicated. The present work proposed an environmentally friendly and facile method, that is, implementing hydrogenation reduction and subsequent calcinations on the nano Si particles immersed in CuCl 2 solution to obtain the Si–Cu 3 Si composite (denoted as Si@Cu 3 Si) with coherent phase boundaries. This architecture helps reduce the contact between Si and electrolyte, depressing the formation of SEI film and the cyclic deterioration of discharge capacity. It not only enhances the cyclic stability by preserving the capacity of 1000 mAhg−1 for 300 cycles, but also improves the rate capability and kinetics of the electrode. Based on detections by X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy, the effects of morphology, composition and structure on the electrochemical performance of the nano-sized Si@Cu 3 Si anode was clarified in the present work. • Facile and environmentally friendly method to prepare Si@Cu 3 Si nano-composite was proposed. • The Si@Cu 3 Si anode exhibits superior cyclic performance, rate capability and electrode kinetics. • Cu 3 Si anchors the Si nano-particles tightly by amorphous boundaries. [ABSTRACT FROM AUTHOR]