Facile fabrication of heterostructure with p-BiOCl nanoflakes and n-ZnO thin film for UV photodetectors

Herein, high-quality n-ZnO film layer on c-sapphire and well-crystallized tetragonal p-BiOCl nanoflakes on Cu foil are prepared, respectively. According to the absorption spectra, the bandgaps of n-ZnO and p-BiOCl are confirmed as ~3.3 and~3.5 eV, respectively. Subsequently, a p-BiOCl/n-ZnO heterostructural photodetector is constructed after a facile mechanical bonding and post annealing process. At –5 V bias, the photocurrent of the device under 350 nm irradiation is ~800 times higher than that in dark, which indicates its strong UV light response characteristic. However, the on/off ratio of In–ZnO–In photodetector is ~20 and the Cu–BiOCl–Cu photodetector depicts very weak UV light response. The heterostructure device also shows a short decay time of 0.95 s, which is much shorter than those of the devices fabricated from pure ZnO thin film and BiOCl nanoflakes. The p-BiOCl/n-ZnO heterojunction photodetector provides a promising pathway to multifunctional UV photodetectors with fast response, high signal-to-noise ratio, and high selectivity.

Morphology-Controlled Growth of A1N One-Dimensional Nanostructures

Aluminum nitride （AIN） nanowires, serrated nanoribbons, and nanoribbons were selectively obtained through a simple chloride assisted chemical vapor deposition process. The morphologies of the products could be controlled by adjusting the deposition position and the flux of the reactant gas. The morphologies and structures of the AIN products were investigated in detail. The formation mechanism of the as-prepared different morphologies of AIN one-dimensional （ID） nanostructures was discussed on the basis of the experimental results.

Bi-based Nanowire and Nanojunction Arrays:Fabrication and Physical Properties

This article reviews the recent developments in the fabrication and properties of one-dimensional （1D） Bi-based nanostructures, including Bi, Sb, BixSb1-x and Bi2Te3 nanowire arrays, and Bi-Bi and Bi-Sb nanojunction arrays. In this article, we present an efiective method to fabricate Bi nanowire arrays with difierent diameters in anodic alumina membrane （AAM） with a single pore size by the pulsed electrodeposition. The fabrication of the high-filling and ordered Bi1-xSbx and Bi2Te3 single crystalline nanowire arrays, the Bi nanowire metalsemiconductor homojunction and Bi-Sb nanowire metal-semiconductor heterojunction arrays by the pulsed electrodeposition are reported. The factors controlling the composition, diameter, growth rate and orientation of the nanowires are analyzed, and the growth mechanism of the nanowire and nanojunction arrays are discussed together with the study of the electrical and thermal properties of Bi-based nanowires and nanojunctions.Finally, this review is concluded with some perspectives on the research directions and focuses in the Bi-based nanomaterials fields.

Transmittance contrast-induced photocurrent:A general strategy for self-powered photodetectors based on MXene electrodes

The regulation of carrier generation and transport by Schottky junctions enables effective optoelectronic conversion in optoelectronic devices.A simple and general strategy to spontaneously generate photocurrent is of great signifi-cance for self-powered photodetectors but is still being pursued.Here,we pro-pose that a photocurrent can be induced at zero bias by the transmittance contrast of MXene electrodes in MXene/semiconductor Schottky junctions.Two MXene electrodes with a large transmittance contrast(84%)between the thin and thick zones were deposited on the surface of a semiconductor wafer using a simple and robust solution route.Kelvin probe force microscopy tests indicated that the photocurrent at zero bias could be attributed to asymmetric carrier generation and transport between the two Schottky junctions under illumination.As a demonstration,the MXene/GaN ultraviolet(UV)photo-detector exhibits excellent performance superior to its counterpart without transmittance contrast,including high responsivity(81 mA W–1),fast response speed(less than 31 and 29 ms)and ultrahigh on/off ratio(1.33�106),and good UV imaging capability.Furthermore,this strategy has proven to be uni-versal for first-to third-generation semiconductors such as Si and GaAs.These results provide a facile and cost-effective route for high-performance self-powered photodetectors and demonstrate the versatile and promising applica-tions of MXene electrodes in optoelectronics.

Decitabine in combination with idarubicin within a modified busulfan/cyclophosphamide conditioning regimen for patients with advanced myelodysplastic syndrome:A prospective multicenter clinical cohort study

To the Editor:Allogeneic hemopoietic stem cell transplantation(allo-HSCT)represents the only long-term survival treatment choice for patients with myelodysplastic syndromes(MDS)and MDS/myeloproliferative neoplasm(MPN).Unfortunately,post-hemopoietic stem cell transplantation(HSCT)relapse remains a cause of treatment failure and the results of salvage treatments are poor.Developing better conditioning regimens is urgently needed.Previous studies have shown synergistic antileukemic effects between decitabine(DEC)and idarubicin(IDA).[1]In an attempt to design a conditioning strategy with very low toxicity but considerable myelosuppressive activity and potential immune-enhancing effects for patients with high-risk MDS and MDS/MPN,we combined DEC and IDA with busulfan,cyclophosphamide,andudarabine for a modied myeloablative regimen in this prospective,multicenter cohort study(hereafter referred to as the“DEC/IDA study”).

Wafer-scale heterogeneous integration of self-powered lead-free metal halide UV photodetectors with ultrahigh stability and homogeneity

Large-scale growth and heterogeneous integration with existing semiconductors are the main obstacles to the application of metal halide perovskites in optoelectronics.Herein,a universal vacuum evaporation strategy is presented to prepare copper halide films with wafer-scale spatial homogeneity.Benefiting from the electric field manipulation method,the built-in electric fields are optimized and further boost the self-powered UV photodetecting performances of common wide-bandgap semiconductors by more than three orders of magnitude.Furthermore,with effective modulation of the interfacial charge dynamics,the as-fabricated GaN-substrate heterojunction photodetector demonstrates an ultrahigh on/off ratio exceeding 107,an impressive responsivity of up to 256 mA W^(-1),and a remarkable detectivity of 2.16×10^(13) Jones at 350 nm,0 V bias.Additionally,the device exhibits an ultrafast response speed(t r/t d=716 ns/1.30 ms),an ultra-narrow photoresponse spectrum with an FWHM of 18 nm and outstanding continuous operational stability as well as long-term stability.Subsequently,a 372-pixel light-powered imaging sensor array with the coefficient of variation of photocurrents reducing to 5.20%is constructed,which demonstrates exceptional electrical homogeneity,operational reliability,and UV imaging capability.This strategy provides an efficient way for large-scale integration of metal halide perovskites with commercial semiconductors for miniature optoelectronic devices.

Two-dimensional perovskite Pb_(2)Nb_(3)O_(10) photodetectors

For the first time,we report high-performance two-dimensional(2D)perovskite Pb_(2)Nb_(3)O_(10) photodetectors(PNO PDs).The few-layer PNO nanosheets are obtained successfully through a simple calcination and liquid exfoliation method.The individual PNO nanosheet devices with various structures(Au-PNO-Au,Au-PNO-Ti,Ti-PNO-Ti)are fabricated and investigated.The Au-PNO-Ti device exhibits a high rectification factor(∼102)owing to a large Schottky barrier difference between the PNO nanosheet and two asymmetric electrodes.Notably,the Au-PNO-Ti device shows excellent self-powered performance,including high responsivity(2.8 A/W),high detectivity(1.1×10^(12) Jones),and fast speed(0.2/1.2 ms)at 350 nm light illumination.This work not only suggests the performance of the PNO nanosheet PDs but also sheds light on the development of high-stability and high-performance devices based on 2D perovskite niobate in the future.

Switch type PANI/ZnO core-shell microwire heterojunction for UV photodetection

In this study,single crystal ZnO microwires(MW)with size of~5.4 mm×30μm are prepared through a chemical vapor deposition technique at high temperature(1200℃).Subsequently,p-type conducting polyaniline(PANI)polymers with different conductivities are densely coated on part of the ZnO MW to construct organic/inorganic core-shell heterojunction photodetectors.The hetero-diodes reach an extremely high rectifcation ratio(I_(+3V)/I_(-3V))of 749230,and a maximum rejection ratio(I_(350nm)/I_(dark))of 3556(at-3 V),indicating great potential as rectifed switches.All the heterojunction devices exhibit strong response to ultraviolet(UV)radiation with high response speed.Moreover,the obvious photovoltaic behavior can also be obtained,allowing the device to operate as an independent and stable unit without externally supplied power.Under 0 V bias voltage,the self-powered photodetector shows a maximum responsivity of 0.56 mA W~(-1)and a rapid response speed of 0.11 ms/1.45 ms(rise time/decay time).Finally,a fnite difference time domain(FDTD)simulation is performed to further demonstrate the interaction mechanism between the incident light feld and the hexagonal cavity,which strongly supports the enhancement of the light absorption in whispering-gallery-mode resonator.

Integration of filter membrane and Ca_(2)Nb_(3)O_(10) nanosheets for high performance flexible UV photodetectors

We report that the integration of filter membrane and Ca_(2)Nb_(3)O_(10)nanosheets(FM@CNO) UV photodetector(UV PD) shows high performance and excellent flexibility. The Ca_(2)Nb_(3)O_(10)nanosheets were prepared by a facile solid-state reaction and liquid exfoliation process. The Ca_(2)Nb_(3)O_(10)nanosheets can be integrated into the pores of a filter membrane via a simple vacuum filtration method. The FM@CNO UV PD shows high performance under 300 nm light illumination at 5 V bias, including high responsivity(0.08 AW^(-1)), high detectivity(1.1 × 10^(12)Jones), high UV/visible rejection ratio(3.86 × 10^(3)) and fast speed(0.12/1.24 ms). Furthermore, the FM@CNO device exhibits excellent flexibility after many bending cycles.In addition, the FM@CNO array device was used as a pixel array detector for UV imaging. This work provides a novel approach to achieve high performance flexible PDs based on filter membrane and two dimensional materials.

Tunable self-powered n-SrTiO3 photodetectors based on varying CuS-ZnS nanocomposite film (p-CuZnS, p-CuS, and n-ZnS)

The heterojunction photodetector between n-SrTiO3(n-STO)and p-CuS-ZnS(p-CZS)is prepared by a simple chemical bath deposition.The p-CZS/n-STO photodetector exhibits excellent self-powered characteristics under 390-nm light illumination,including high photosensitivity(on/off ratio of 300),fast response speed(0.7/94.6 ms),and good wavelength selectivity(410-380 nm).More importantly,the self-powered n-STO photodetectors can be regulated by varying the composition of CZS film(p-CZS,p-CuS,and n-ZnS).All devices exhibit a large opencircuit voltage and show different self-powered behaviors because of the different built-in electric fields.The open-circuit voltages of the CZS/STO,CuS/STO,and ZnS/STO devices are measured to be 0.56,0.30,and 0.35 V,respectively.This work provides a simple and effective way to fabricate tunable self-powered photodetectors by varying the composition of the nanocomposite film.

Flexible 2D Cu Metal:Organic Framework@MXene Film Electrode with Excellent Durability for Highly Selective Electrocatalytic NH_(3) Synthesis

Electrocatalytic nitrate reduction to ammonia(ENRA)is an effective strategy to resolve environmental and energy crisis,but there are still great challenges to achieve high activity and stability synergistically for practical application in a fluid environment.The flexible film electrode may solve the abovementioned problem of practical catalytic application owing to the advantages of low cost,light weight,eco-friendliness,simple and scalable fabrication,extensive structural stability,and electrocatalytic reliability.Herein,2D hybridization copper 1,4-benzenedi-carboxylate(CuBDC)has been grown on electronegative MXene nanosheets(Ti_(3)C_(2)T_(x))seamlessly to prepare a 2D flexible CuBDC@Ti_(3)C_(2)T_(x)electrode for ENRA.The flexible electrode simultaneously exhibits high Faradaic efficiency(86.5%)and excellent stability for NH_(3)synthesis,which are comparable to previously reported nanomaterials toward ENRA.Especially,the flexible electrode maintains outstanding FENH_(3)toward ENRA after the bending,twisting,folding,and crumpling tests,indicating excellent electroconductibility,high stability,and durability.This work not only provides mild permeation-mediated strategy to fabricate a flexible electrode but also explores the practical applications of the electrode with effectively environmental adaptability in solving global environmental contamination and energy crisis by effective ENRA.