Thermally activated fluorescence in 9,10-DPA single crystals enabling high-performance fast neutron detection.

Organic scintillators occupy a significant niche in the realm of fast neutron detection. Nevertheless, the cultivation of large-sized and high-quality organic single crystals has persistently posed a formidable challenge. 9,10-diphenylanthracene (DPA) was chosen as a prospective material for fast neutron detection.

Capillary Force-Assisted CsPbBrI ( = 0, 1) Columnar Crystal Film for X-ray Detectors with Ultrahigh Electric Field and Sensitivity.

Inorganic halide perovskite thin-film X-ray detectors have attracted great research interest in recent years due to their high sensitivity, low detection limit, and facile fabrication process. The poor crystal quality of the thin film with uncontrollable thickness and low background voltage during detection limits its practical application. Here, a high-quality CsPbBrI ( = 0, 1) columnar crystal film is prepared by an improved melt-confined method with a porous anodic aluminum oxide (AAO) template, which stabilizes the disorder perovskite systems of CsPbBrI by stress.

High energy resolution CsPbBr alpha particle detector with a full-customized readout application specific integrated circuit.

α particles must be monitored to be managed as radioactive diagnostic agents or nuclear activity indicators. The new generation of perovskite detectors suffer from limited energy resolution, which affects spectroscopy and imaging applications. Here, we report that the solution-grown CsPbBr crystal exhibits a low and stable dark current (34.

Selenophosphate PbPSe Single Crystals Growth by Chemical Vapor Transport (CVT) Method for Radiation Detection.

The heavy metal selenophosphate PbPSe emerges as a promising room-temperature X-ray/γ-ray detectors due to its high resistivity, robust radiation-blocking capability, and outstanding carrier mobility-lifetime product, etc. However, the high activity of phosphides poses significant impediment to the synthesis and single crystal growth. In this work, we have prepared high-quality PbPSe single crystals with using the chemical vapor transport (CVT) method.

Heavy-to-light electron transition enabling real-time spectra detection of charged particles by a biocompatible semiconductor.

The current challenge of wearable/implantable personal dosimeters for medical diagnosis and radiotherapy applications is lack of suitable detector materials possessing both excellent detection performance and biocompatibility. Here, we report a solution-grown biocompatible organic single crystalline semiconductor (OSCS), 4-Hydroxyphenylacetic acid (4HPA), achieving real-time spectral detection of charged particles with single-particle sensitivity. Along in-plane direction, two-dimensional anisotropic 4HPA exhibits a large electron drift velocity of 5 × 10cm s at "radiation-mode" while maintaining a high resistivity of (1.

High-Performance Industrial-Grade CsPbBr Single Crystal by Solid-Liquid Interface Engineering.

All-inorganic metal halide perovskite CsPbBr crystal is regarded as an attractive alternative to high purity Ge and CdZnTe for room temperature γ-ray detection. However, high γ-ray resolution is only observable in small CsPbBr crystal; more practical and deployable large crystal exhibits very low, and even no detection efficiency, thereby thwarting prospects for cost-effective room temperature γ-ray detection. The poor performance of large crystal is attributed to the unexpected secondary phase inclusion during crystal growth, which traps the generated carriers.

Improved Crystallization Quality of FAPbBr Single Crystals by a Seeded Solution Method.

Solution-grown hybrid perovskite, FAPbBr, has attracted great attentions recently due to its inspiring optoelectronic properties and low-cost preparation method. However, challenges of solution growth for FAPbBr bulk crystals remain yet, such as uncontrollable crystalline morphologies, irregular shapes, and limited crystal sizes, which are attributed to the dense crystallization nucleus. In this work, we investigate the effects of growth conditions and seed behaviors on the crystallization quality and the yield of FAPbBr single crystals.

Oriented preparation of Large-Area uniform CsTeI perovskite film for high performance X-ray detector.

Large-area flexible perovskite films are attracting widespread research interest for applications in wearable solar cells, portable photodetectors, bendable X-ray imaging detectors and other implantable optoelectronic devices. In this work, a facile mobile platform assisted electrospray method is developed to prepare large-area (100 cm) lead-free CsTeI film on flexible polyimide substrate. The spraying parameters are coupled with the growth temperature to achieve a dynamic balance.

Unusual Deformation and Fracture in Gallium Telluride Multilayers.

The deformation and fracture mechanism of two-dimensional (2D) materials are still unclear and not thoroughly investigated. Given this, mechanical properties and mechanisms are explored on example of gallium telluride (GaTe), a promising 2D semiconductor with an ultrahigh photoresponsivity and a high flexibility. Hereby, the mechanical properties of both substrate-supported and suspended GaTe multilayers were investigated through Berkovich-tip nanoindentation instead of the commonly used AFM-based nanoindentation method.

Effects of Si and Sr elements on solidification microstructure and thermal conductivity of Al-Si-based alloys.

Unlabelled: Effects of Si and Sr on solidification microstructure and thermal conductivity of Al-Si binary alloys and Al-9Si-Sr ternary were investigated, respectively, with a special focus on the relationship between solidification microstructure and thermal conductivity. It was found that (i) in Al-Si binary alloys, with increasing Si content, α-Al grain size increases and then decreases when Si content is over 7 wt%, while the percentage of eutectic Si continuously increases, which significantly decreases the thermal conductivity and electrical conductivity, and (ii) in Al-9Si-Sr ternary alloys, the presence of Sr has no significant effect on α-Al grain, but effectively modifies eutectic Si and significantly improves the thermal and electrical conductivity. On this basis, two theoretical calculation models [the Maxwell model and the Hashin-Shtrikman (H-S) model] were used to elucidate the relationship between solidification microstructure and thermal conductivity.

Two-Dimensional Dion-Jacobson Perovskite (NHCHNH)CsPbBr with High X-ray Sensitivity and Peak Discrimination of α-Particles.

Two-dimensional (2D) halide perovskites have attracted extensive interest because of their excellent optoelectronic properties, structural diversity, and promising stability. Herein, we grow a novel 2D Dion-Jacobson halide perovskite, (BDA)CsPbBr (BDA = 1,4-butanediamine, NHCHNH), which exhibits a large bandgap (∼2.76 eV), high resistivity (∼4.

High-Stability Flexible X-ray Detectors Based on Lead-Free Halide Perovskite CsTeI Films.

Normal flat panel X-ray detectors are confined in imaging of curved surfaces and three-dimensional objects. Except that, their rigid panels provide uncomfortable user experience in medical diagnosis. Here, we report a flexible X-ray detector fabricated by the combination of a lead-free CsTeI perovskite film and a polyimide (PI) substrate.

Solution-Grown Formamidinium Hybrid Perovskite (FAPbBr) Single Crystals for α-Particle and γ-Ray Detection at Room Temperature.

Compared with the widely reported MAPbBr single crystals, formamidinium-based (FA-based) hybrid perovskites FAPbBr (FPB) with superior chemical and structure stability are expected to be more efficient and perform as more reliable radiation detectors at room temperature. Here, we employ an improved inverse temperature crystallization method to grow FPB bulk single crystals, where issues associated with the retrograde solubility behavior are resolved. A crystal growth phase diagram has been proposed, and accordingly, growth parameters are optimized to avoid the formation of NHPbBr secondary phase.

Anisotropic dielectric behavior of layered perovskite-like CsBiI crystals in the terahertz region.

The ternary metal halide perovskites have gradually attracted attention for application in the optoelectronic field, owing to their tunable crystal structure and appropriate bandgap. Lead free CsBiI perovskite, with a 0D layered structure containing molecular [BiI] dimers, exhibits prominent optical and electrical anisotropies. Here, the anisotropic properties of the CsBiI crystals were evaluated using terahertz time-domain spectroscopy (THz-TDS); meanwhile, the effect of phonon vibration on the THz transmission was confirmed using density functional perturbation theory (DFPT).

Secondary Phase Particles in Cesium Lead Bromide Perovskite Crystals: An Insight into the Formation of Matrix-Controlled Inclusion.

The metal halide perovskite CsPbBr bulk crystals present electrical and optical performance discrepancy since the grown-in defects. Here, we first report the well-defined secondary phase (SP) particles of CsPbBr with polyhedral morphology in CsPbBr crystals grown by the vertical Bridgman method. The resulting polyhedral morphology of CsPbBr particles associated with the trapping of PbBr-rich droplets have been discussed on the basis of the "matrix-controlled" growth.

Effect of Deep-Level Defects on the Performance of CdZnTe Photon Counting Detectors.

The effect of deep-level defects is a key issue for the applications of CdZnTe high-flux photon counting devices of X-ray irradiations. However, the major trap energy levels and their quantitive relationship with the device's performance are not yet clearly understood. In this study, a 16-pixel CdZnTe X-ray photon counting detector with a non-uniform counting performance is investigated.

Au-InSe van der Waals Schottky junctions with ultralow reverse current and high photosensitivity.

The Schottky junction, composed of a rectifying metal-semiconductor interface, is an essential component for microelectronic and optoelectronic devices. However, due to the considerable reverse tunneling current, typical Schottky junctions cannot be widely applied in devices requiring high signal-to-noise ratios, such as photodetectors with high detectivity. Here, a van der Waals (vdW) Schottky junction is constructed by mechanically stacking a gold (Au) electrode onto a multilayer indium selenide (InSe) nanosheet, which shows an ultralow reverse current in sub-picoamperes and an excellent rectification ratio exceeding 10 at room temperature.

Investigation on X-Ray Photocurrent Response of CdZnTe Photon Counting Detectors.

Counting rate is an important factor for CdZnTe photon counting detectors as high-flux devices. Until recently, there has been a lack of knowledge on the relationship between X-ray photocurrent response and the photon counting performance of CdZnTe detectors. In this paper, the performance of linear array 1 × 16-pixel CdZnTe photon counting detectors operated under different applied biases is investigated.

Effects of interlayer interactions on the nanoindentation response of freely suspended multilayer gallium telluride.

Freestanding indentation is a widely used method to characterise the elastic properties of two-dimensional (2D) materials. However, many controversies and confusion remain in this field due to the lack of appropriate theoretical models in describing the indentation responses of 2D materials. Taking the multilayer gallium telluride (GaTe) as an example, in this paper we conduct a series of experiments and simulations to achieve a comprehensive understanding of its freestanding indentation behaviours.

Passivation of Layered Gallium Telluride by Double Encapsulation with Graphene.

Layered semiconductor gallium telluride (GaTe) undergoes a rapid structural transition to a degraded phase in ambient conditions, limiting its utility in devices such as optical switches. In this work, we demonstrate that the degradation process in GaTe flakes can be slowed down dramatically via encapsulation with graphene. Through examining Raman signatures of degradation, we show that the choice of substrate significantly impacts the degradation rate and that the process is accelerated by the transfer of GaTe to hydrophilic substrates such as SiO/Si.

Improvement to the Carrier Transport Properties of CdZnTe Detector Using Sub-Band-Gap Light Radiation.

The effects of sub-band-gap light radiation on the performance of CdZnTe photon-counting X-ray detectors were studied using infrared light with different wavelengths in the region of 980⁻1550 nm. The performance of the detectors for X-ray detection was improved by the radiation of infrared light with the wavelengths of 1200 nm and 1300 nm. This was because the increase of the electron indirect transition, and the weakening of the built-in electric field induced by the trapped holes, reduced the drift time of the carrier, and increased the charge collection efficiency.

Enhanced X-ray Sensitivity of MAPbBr Detector by Tailoring the Interface-States Density.

An important factor for the high performance of light-harvesting devices is the presence of surface trappings. Therefore, understanding and controlling the carrier recombination of the organic-inorganic hybrid perovskite surface is critical for the device design and optimization. Here, we report the use of aluminum zinc oxide (AZO) as the anode to construct a p-n junction structure MAPbBr nuclear radiation detector.

High-Quality GaSe Single Crystal Grown by the Bridgman Method.

A high-quality GaSe single crystal was grown by the Bridgman method. The X-ray rocking curve for the studied GaSe sample is symmetric and the Full Width at Half Maximum (FWHM) is only 46 arcs, which is the smallest value ever reported for GaSe crystals. The IR-transmittance is about 66% in the range from 500 to 4000 cm.

Microwatts continuous-wave pumped second harmonic generation in few- and mono-layer GaSe.

We demonstrate the first achievement of continuous-wave (CW) pumped second harmonic generation (SHG) in few- and mono-layer gallium selenide (GaSe) flakes, which are coated on silicon photonic crystal (PC) cavities. Because of ultrahigh second order nonlinearity of the two-dimensional (2D) GaSe and localized resonant mode in the PC cavity, SHG's pump power is greatly reduced to microwatts. In a nine-layer GaSe coated PC cavity, while the optical power inside the GaSe flake is only 1.