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Platinum (Pt) nanocrystals hold the key to a variety of catalytic applications, and those with a cubic shape are attractive as a reference catalyst due to their well-defined {100} facets on the surface. Here we demonstrate the use of droplet reactors as a viable platform for the continuous and scalable production of Pt nanocubes with uniform and controllable sizes. The synthesis was found to be sensitive to the O

Efficient and fast scintillators are in high demand for a variety of fields, such as medical diagnostics, scientific instruments, and high-energy physics. However, the trade-off between high scintillation efficiency and fast timing properties is a common challenge faced by almost all scintillators. To overcome this limitation, we have developed a new strategy for organic scintillators by directing all hot excitons into fast singlet emission states without involving the lowest triplet states. Our scintillator 1,1,2,2-tetraphenylethylene (4-bromophenyl) (TPE-4Br) shows an ultrafast radiative lifetime of 1.79 ns and ~ 72600 photons MeV− 1 light yield, exhibiting an unprecedented combination of high light yield and short decay time. Our work provides a paradigm-shifting method to design efficient and ultrafast scintillators and paves the way towards exciting applications toward ultrafast detection and imaging.

Long-term and high-speed 3D imaging of live cells beyond diffraction limit remains a big challenge for current super-resolution microscopy implementations, owing to their severe phototoxicity and limited volumetric imaging rate. While emerging light-field microscopy (LFM) has mitigated this issue through rapid and mild 3D imaging of dynamic biological processes with single 2D snapshots, it suffers from a suboptimal spatial resolution close to diffraction limit, which greatly compromises its applications for live-cell imaging. Here, we propose a super-resolution light-field reconstruction strategy based on an optics-aware view-channel-depth (VCD 2.0) deep-learning strategy. Through a stepwise inversion of the physical degradation process during light-filed imaging, VCD 2.0 strongly pushes the light-field microscopy beyond diffraction limit, and achieves instant 3D reconstructions from raw 2D light-field snapshots with an ∼14-fold resolution improvement. After being combined with a simple-and-robust light-field add-on design, VCD 2.0 further enables long-term 3D super-resolution imaging (over 30000 volumes) of various intracellular dynamics (FOV of ∼220×220×10 μm3) even on an ordinary 2D fluorescence microscope. Using this novel and readily-accessible approach, we successfully capture the fast morphology changes of diverse organelles, such as the extension and constriction in lysosome, at a near isotropic resolution of ∼120 nm, and a high volume rate up to 50 Hz.

Low-dimensional organic-metal halides are regarded as an emerging class of X-ray scintillation materials, but most of the discovered compounds are confronted with challenges of toxicity and instability. To address these challenges, we herein report two lead-free zero-dimensional (0D) hybrid halides, (Bmpip)

Two-dimensional (2D) multilayer Dion-Jacobson (DJ) phase organic inorganic hybrid perovskites (OIHPs) have attracted extensive research attention due to the high stability and excellent charge-transport properties in the optoelectronic field. However, the synthesis of 2D multilayer DJ OIHPs is still very challenging. Until now, only few multilayer DJ perovskites have been reported and most of them are based on volatile methylamine (MA) cations. Compared with MA-based OIHPs, the OIHPs constructed with formamidinium (FA) as perovskitizers not only improve the stability but also extend the light absorption range. Meanwhile, the introducing aromatic diamines as spacers could promote the electron-hole separation in such DJ hybrids. However, the DJ OIHP bulk single crystal constructed by using the advantages of FA as perovskitizers and aromatic diamines as spacers is still blank. Herein, we integrate the properties of organic cations and inorganic skeletons at a molecular-scale to construct a broadband-responsive 2D bilayer DJ perovskite (3AMPY)(FA)Pb

Advances and challenges in patterning of perovskite materials and fabrication of optoelectronic devices using IJP technologies are presented.

The metal halide perovskites exhibit excellent performance as the direct X-ray detectors owing to their strong absorption capability, long carrier lifetime and diffusion length, radiation ruggedness, etc. For imaging applications, the ionic migration of perovskites and charge sharing effect between the adjacent pixels have a significantly negative impact on the spatial resolution. Herein, for the first time, the porous anodic aluminum oxides (AAO) have been used as a template to grow the CsPbBr2I thick film for the direct X-ray detection. Benefiting from the oxygen passivation effect, the activation energy for ionic migration has been observed to increase to 0.701 eV, whereas the dark current drift (1.01 × 10−5 nA cm−1s−1V−1) is one to two orders of magnitude lower than the other lead halide perovskite single crystals and films. Moreover, the AAO insulating wall effectively blocks the charge diffusion effect across a pixel pitch of 10 μm. Overall, the findings reported in this study open a new route for reducing the ionic migration and pixel crosstalk, thus, bringing the perovskite X-ray detectors close to the practical applications.

International audience; Glass scintillators have several benefits compared to the currently used single or polycrystalline scintillators, including non-hygroscopicity, mechanical ruggedness, ease of producing customizable shapes, and low-cost synthesis. The combination of the inert glass matrix and the embedded highly scintillating center render them significant materials for medical imaging and therapy, non-destructive probing, nuclear monitoring, and high-energy physics. Recently, great progress has been made in exploring new kinds of glass scintillator materials, improving imaging resolution for radiation detection, and developing an enormous range of commercial products. However, the majority of efforts have been devoted to the variation of materials, while rationally designing this new family of scintillators toward expected properties and applications is still lacking. In this review, the focus is specifically on advances in glass scintillators, including the scintillation fundamentals, material designing rule, and current application status, as well as future challenges and future directions.

International audience; 2D Ruddlesden-Popper (RP) perovskites have demonstrated highperformance emitters, and large-sized perovskite single crystals have always been pursued for efficient optoelectronic devices. However, large-sized 2D RP perovskite single crystals with high quality are still difficult to achieve due to the weak interaction between layers and strong anisotropy. Here, we show a rational design strategy to synthesize centimeter-sized 2D BM2PbBr4 (BM = benzimidazole) perovskite single crystals by intermediate-phase engineering (IPE). 1D (DMF)2BMPbBr3 intermediate-phase single crystals were structurally decoupled and transformed to perfect 2D BM2PbBr4 seed crystals with a certain thickness, presenting a huge advantage over the extrathin crystal sheets in random stacking by natural crystallization. Furthermore, the new BM with conjugated structures we obtained as the A-site of the 2D RP perovskite enhances the exciton confinement, resulting in a surprisingly large excitonic binding energy of 368.2 meV. The emitting decay time is shortened to 0.98 ns, which is the smallest among all the perovskite materials. Tailoring of the X-site components for 2D RP BM2PbBr4 - xClx (x = 1, 2, 3, and 4) series with tunable luminescence and decay time was also synthesized by IPE. We believe IPE provides a new way for synthesizing large-sized perovskite single crystals with fine-tunable properties to satisfy the target applications.

X-ray detection is of great significance in biomedical, nondestructive, and scientific research. Lead halide perovskites have recently emerged as one of the most promising materials for direct X-ray detection. However, the lead toxicity remains a worrisome concern for further commercial application. Great efforts have been made to search for lead-free perovskites with similar optoelectronic properties. Here, we present a lead-free oxide double perovskite material Ba(2)AgIO(6) for X-ray detection. The lead-free, all-inorganic nature, as well as the high density of Ba(2)AgIO(6), promises excellent prospects in X-ray applications. By employing the hydrothermal method, we successfully synthesized highly crystalline Ba(2)AgIO(6) powder with pure phase. Furthermore, we prepared Ba(2)AgIO(6) wafers through isostatic pressure and built X-ray detectors with Au/Ba(2)AgIO(6) wafer/Au photo-conductive structure. The as-prepared X-ray detectors showed a sensitivity of 18.9 µC/(Gy(air)·cm(2)) at 5 V/mm, similar to commercial α-Se detectors showcasing their advantages for X-ray detection. [Image: see text]

The present work reports highly efficient flexible and reabsorption-free scintillators based on two zero-dimensional (0D) organic copper halides (TBA)CuX2 (TBA = tetrabutylammonium cation; X = Cl, Br). The (TBA)CuX2 exhibit highly luminescent green and sky-blue emissions peaked at 510 and 498 nm, with large Stokes shifts of 224 and 209 nm and high photoluminescence quantum yields (PLQYs) of 92.8% and 80.5% at room temperature for (TBA)CuCl2 and (TBA)CuBr2 single crystals (SCs), respectively. Interestingly, above room temperature, their PLQYs increase with temperature and reach near unity at 320 and 345 K for (TBA)CuCl2 and (TBA)CuBr2, respectively. The excellent properties originate from self-trapped excitons (STEs) in individual [CuX2]- quantum rods, which is demonstrated by the temperature-dependent PL, ultrafast transient absorption (TA) combined with density functional theory (DFT) calculations. The (TBA)CuX2 scintillators show bright radioluminescence (RL), impressive linear response to dose rate in a broad range, and high light yields. Their potential application in X-ray imaging is demonstrated by using (TBA)CuX2 composite scintillation screens. Importantly, flexible scintillators are demonstrated to be superior than flat ones for imaging nonplanar objects by conformally coating, which produce accurate images with negligible distortion.

An all-inorganic lead-free halides Cs-Cu-I system, represented by Cs3Cu2I5 and CsCu2I3, has attracted attention for their good photophysical characteristics recently. Successive works had reported their application potential in light-emitting devices. However, there is no report for CsCu2I3 in X-ray scintillation detectors so far. We notice that CsCu2I3 may be advantageous in such an application due to the one-dimensional crystal structure, the congruent-melting feature, and the high spectral matching to some photosensors. In this work, we explore the scintillation properties and imaging application of CsCu2I3 in X-ray scintillator detector. The oriented structure is designed to enhance the imaging performance of a CsCu2I3 detector. Close-space sublimation process and nanoscale seed screening strategy are employed to realize this design by producing a large-area (25 cm2) CsCu2I3 thick film layer with the oriented nanorod structure. This CsCu2I3 detector eventually achieves a high spatial resolution of 7.5 lp mm-1 in X-ray imaging.

All-inorganic lead-free halide perovskites have attracted interest owing to their high ambient and thermal stabilities, excellent optoelectronic properties, and environmental friendliness. Herein, the bismuth-based halide perovskite Cs3Bi2Br9 single crystals were successfully grown to a diameter of 12 mm and length of 40 mm using a modified Bridgman method for the first time. The resistivity and transmittance of transparent and crack-free Cs3Bi2Br9 single crystal are ~6.8×1011 Ω cm and ~80%, respectively. The carrier mobility of the (−120) plane is 0.17 cm2 V−1 s−1 along the [010] orientation (b axis), and the trap density is 9.7×1010 cm−3. Moreover, Cs3Bi2Br9 single crystals exhibit excellent potential for X-ray detection, including a high absorption coefficient, a superior X-ray sensitivity of ~230.4 µC Gyair−1 cm−2, and an ultra-low and no-drift dark current density of ~17.8 pA mm−2, which enables lower noise and is also beneficial to the ultra-low detection limit for X-ray detectors. Our study shows that Cs3Bi2Br9 is a promising candidate for X-ray detection applications.

Summary Metal halide perovskites (MHP) have demonstrated excellent X-ray detection performance, thanks to their compelling properties including large mobility-lifetime product, strong X-ray absorption, and easy synthesis, etc. The latest progress and future perspective of MHP-based X-ray detection and imaging are reviewed herein. The fundamental knowledge of X-ray interaction with materials and the characteristics of direct and indirect (via scintillators) X-ray detection is first discussed. We then introduce the methods for scalable fabrication of MHP and summarize their recent device performance. We further present the integration of MHP detectors with readout integrated circuits and the associated performance metrics for flat panel detector (FPD). We also briefly talk about ways to minimize cross-talk and increase spatial resolution in FPDs. Last, we provide some cautions to evaluate the detector performance and some suggestions to further improve the performance. We hope this paper can help readers understand the status and future challenges for perovskite X-ray detectors.

Lead halide perovskites have demonstrated excellent performance for light emitting diodes and detectors. However, the toxicity of lead (Pb) in the devices severely impedes their widespread application and commercialization. The design of lead-free perovskites for environmentally friendly devices is an imperative mission, but full of challenges. In this perspective, we mainly discuss the design strategy of lead-free perovskites, as well as theoretical understanding and experimental demonstrations of their electronic and optical properties. The present status and future prospects of each lead-free perovskite are also summarized in the review, which could give a better understanding and right direction for the further exploration of satisfactory optoelectronic devices. We also provide the up-to-date progress of lead-free perovskites in the applications of light-emitting devices and radiation detectors.

Direct X-ray detectors are considered as competitive next-generation X-ray detectors because of their high spatial resolution, high sensitivity, and simple device configuration. However, their potential is largely limited by the imperfections of traditional materials, such as the low crystallization temperature of α-Se and the low atomic numbers of α-Si and α-Se. Here, we report the Sb(2)Se(3) X-ray thin-film detector with a p-n junction structure, which exhibited a sensitivity of 106.3 µC/(Gy(air)·cm(2)) and response time of < 2.5 ms. This decent performance and the various advantages of Sb(2)Se(3), such as the average atomic number of 40.8 and μτ product (μ is the mobility, and τ is the carrier lifetime) of 1.29 × 10(−5) cm(2)/V, indicate its potential for application in X-ray detection. [Image: see text]

Lead halide perovskites have shown great X-ray scintillation properties. One big challenge is to find nontoxic replacements for practical applications. Moreover, the scintillator should contain les...

Metal halide perovskites have recently been reported as excellent scintillators for X-ray detection. However, perovskite based scintillators are susceptible to moisture and oxygen atmosphere, such as the water solubility of CsPbBr3, and oxidation vulnerability of Sn2+, Cu+. The traditional metal halide scintillators (NaI: Tl, LaBr3, etc.) are also severely restricted by their high hygroscopicity. Here we report a new kind of lead free perovskite with excellent water and radiation stability, Rb2Sn1-x Te x Cl6. The equivalent doping of Te could break the in-phase bonding interaction between neighboring octahedra in Rb2SnCl6, and thus decrease the electron and hole dimensionality. The optimized Te content of 5% resulted in high photoluminescence quantum yield of 92.4%, and low X-ray detection limit of 0.7 µGyair s−1. The photoluminescence and radioluminescence could be maintained without any loss when immersing in water or after 480,000 Gy radiations, outperforming previous perovskite and traditional metal halides scintillators.

Though CH3NH3PbBr3 single crystals are frequently applied in various optoelectronic devices due to their favorable cuboid geometry, superior optoelectronic properties, and better stability than CH3NH3PbI3, CH3NH3PbBr3 polycrystalline films normally show poorer morphology with scattered crystals than their iodide counterparts, inherently due to their different crystallization habits. In this work, a facile process based on a hot methylamine-based precursor with high viscosity and concentration is demonstrated to counteract rapid ion diffusion. The precursor also has special features including a large colloidal size, a solid form at room temperature, and fast crystallization offered by the easy evacuation of methylamine. CH3NH3PbBr3 films composed of tightly aligned CH3NH3PbBr3 cuboids on micron scale are obtained. Wide channel (100 μm) photodetectors made from the CH3NH3PbBr3 films show promising photoresponse and fast response speeds on par with those based on single crystals, suggesting high film quality and good optoelectronic connections between neighboring cuboids.

Self-trapped excitons (STEs) in metal halide materials are attracting an increasing level of interest due to their unique light emission properties. Light emission from STEs in metal halides is usu...