Ultrafast Speed Research Articles

An ultra-fast deep-learning-based dose engine for prostate VMAT via knowledge distillation framework with limited patient data

Objective. Deep-learning (DL)-based dose engines have been developed to alleviate the intrinsic compromise between the calculation accuracy and efficiency of the traditional dose calculation algorithms. However, current DL-based engines typically possess high computational complexity and require powerful computing devices. Therefore, to mitigate their computational burdens and broaden their applicability to a clinical setting where resource-limited devices are available, we proposed a compact dose engine via knowledge distillation (KD) framework that offers an ultra-fast calculation speed with high accuracy for prostate Volumetric Modulated Arc Therapy (VMAT). Approach. The KD framework contains two sub-models: a large pre-trained teacher and a small to-be-trained student. The student receives knowledge transferred from the teacher for better generalization. The trained student serves as the final engine for dose calculation. The model input is patient computed tomography and VMAT dose in water, and the output is DL-calculated patient dose. The ground-truth \\dose was computed by the Monte Carlo module of the Monaco treatment planning system. Twenty and ten prostate cases were included for model training and assessment, respectively. The model’s performance (teacher/student/student-only) was evaluated by Gamma analysis and inference efficiency. Main results. The dosimetric comparisons (input/DL-calculated/ground-truth doses) suggest that the proposed engine can effectively convert low-accuracy doses in water to high-accuracy patient doses. The Gamma passing rate (2%/2 mm, 10% threshold) between the DL-calculated and ground-truth doses was 98.64 ± 0.62% (teacher), 98.13 ± 0.76% (student), and 96.95 ± 1.02% (student-only). The inference time was 16 milliseconds (teacher) and 11 milliseconds (student/student-only) using a graphics processing unit device, while it was 936 milliseconds (teacher) and 374 milliseconds (student/student-only) using a central processing unit device. Significance. With the KD framework, a compact dose engine can achieve comparable accuracy to that of a larger one. Its compact size reduces the computational burdens and computing device requirements, and thus such an engine can be more clinically applicable.

Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy

The highly effective utilization of uranium resources in global seawater is a viable method to satisfy the rising demands for fueling nuclear energy industry. Herein, inspired by the multi-mechanisms of the marine bacteria for uranium immobilization, CdS nanoparticles are deposited on the cell of marine bacterial strain Bacillus velezensis UUS-1 to create a photosensitized biohybrid system UUS-1/CdS. This system achieves high uranium extraction efficiency using a cascaded strategy, where the bacterial cells guarantee high extraction selectivity and the photosensitive CdS nanoparticles realize cascading photoreduction of high soluble U(VI) to low soluble U(IV) to enhance extraction capacity. As one of the fastest-acting adsorbents in natural seawater, a high extraction capacity for uranium of 7.03 mg g−1 is achieved with an ultrafast extraction speed of 4.69 mg g−1 d−1. The cascaded strategy promisingly improves uranium extraction performance and pioneers a new direction for the design of adsorbents to extract uranium from seawater.

High-performance Ga2O3/FTO-based self-driven solar-blind UV photodetector with thickness-optimized graphene top electrode

Self-driven solar-blind ultraviolet photodetectors (SBUVPDs) have attracted considerable interest for their superior sensitivity and operation flexibility. Herein, we demonstrate realization of a simple vertical-structured self-driven SBUVPD by pulsed laser deposition of β-Ga2O3 thin film on commercially available fluorine doped tin oxide (FTO) substrate, adopting multi-layer graphene (MLG) as the top electrode. On the one hand, the introduction of MLG with both high electrical conductance and UV transmittance greatly enhances photocurrent and responsivity of the photodetector. On the other hand, the dominating Schottky contact between Ga2O3 and MLG creates a net built-in electric field, leading to self-driven photoresponse of the device with improved response speed. With optimized thickness (8 ± 2 single layers of graphene) of the top electrode, the device exhibits the best detection performance that is superior to most of previous reports towards UV illumination at 0 V bias. It delivers a photocurrent as high as 31 nA towards 250 nm-light with ultra-fast response speed (τr = 2 ms, τd = 8.8 ms), and exhibits a maximum responsivity of 9.2 mA/W and detectivity of 5.27 × 1011 Jones under 230 nm-light illumination, while the response cuts off at light wavelength of 261 nm, falling completely within the solar blind band. In addition, the device has good multi-cycle repeatability and stability, showing great application potential in solar-blind UV detection.

Fast and hydrosensitive switching of plasmonic nanocavities via photothermal effect

Metallic nanoplasmonics, due to its extremely small size and ultrafast speed, has been one of the key components for next-generation information technology. It is vital that the highly tunable nanoplasmonic system in the solid state can be achieved for optoelectronic devices, which, still remains elusive for the visible region. Here we sandwich vanadyl oxalate ( VOC 2 O 4 ) thin films in-between gold nanoparticles and gold film to establish thermo-responsive nanoantennas. The thickness of the VOC 2 O 4 composite films remains almost unchanged within the temperature cycles between 15°C and 80°C, while the refractive index of the films decreases with the increase of temperature due to the dehydration, which results in blueshift of the plasmon peak up to 60 nm. The plasmon resonances can be fully recovered when the temperature cools down again. This process is reversible within the temperature range of 15°C–80°C, which can be optically modulated with photothermal effect. Such thermo-responsive plasmonic nanoantenna works in the solid state with hundreds of kilohertz switching speed, which is highly compatible with traditional optoelectronic devices. It can be envisioned that this thermo-responsive optical thin film can be a promising candidate for integrated nanoplasmonic and optoelectronic devices.

Exploration of threshold and resistive-switching behaviors in MXene/BaFe12O19 ferroelectric memristors

Ferroelectric memristors have great potentials to be the key computational element of the brain-inspired neuromorphic system due to their excellent endurance, multi-bit storage ability, ultrafast speed, and ultra-low energy consumption. In this work, novel barium ferrite (BFO: BaFe12O19)-based ferroelectric memristors have been fabricated. Meanwhile, two-dimensional MXene Ti3C2 was inserted onto the dielectric layer for performance enhancement. More importantly, under the regulation of compliance currents, the Cu/Ti3C2/BFO/Pt ferroelectric memristors can convert from stable threshold-switching (TS) to resistive-switching (RS) behavior. The coexistence of the TS and RS demonstrated in this work facilitates the simulation of biological synapses, i.e., short/long-term plasticity, paired-pulse facilitation, and spike-time-dependent plasticity. In addition, the one-bit adder circuit by fitting the non-volatile I-V curve (RS behavior) was demonstrated in the Cadence Virtuoso environment. The deep neural network based on our ferroelectric crossbar arrays has been architected for the image classification (on-chip: 85 %) of the CIFAR-10 dataset. The internal mechanisms are attributed to the combination of barrier variation induced by the ferroelectric polarization and motion of oxygen vacancies, which have been verified by the first-principles calculation of density functional theory. These results may provide possible suggestions for ferroelectric memristors-based neuro-inspired computing systems.

Spin-Orbit-Torque Switching of Ferrimagnets by Terahertz Electrical Pulses

In conventional spintronic devices, ferromagnetic materials are used, which have a magnetization dynamics timescale of around nanoseconds, setting a limit for the switching speed. Increasing the magnetization switching speed has been one of the major challenges for spintronic research. In this work we take advantage of the ultrafast magnetic dynamics in ferrimagnetic materials instead of ferromagnets, and we use femtosecond laser pulses and a plasmonic photoconductive switch to create THz electrical pulses for ferrimagnetic switching by spin-orbit torque. By anomalous Hall and magneto-optic Kerr effect (MOKE) measurement, we demonstrate the robust THz-electrical-pulse-driven magnetization switching of ferrimagnetic $\mathrm{Gd}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$. The time-resolved MOKE shows more than 50-GHz magnetic resonance frequency of $\mathrm{Gd}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Co}$, indicating faster than 20-ps magnetic dynamics. X-ray magnetic circular dichroism demonstrates the antiferromagnetically coupled $\mathrm{Fe}$ and $\mathrm{Gd}$ sublattices. Our work provides a promising route to realize ultrafast operation speed for nonvolatile magnetic memory and logic applications.

Recent Progress in Organic-Based Photonic Synapses

Organic photonic synapses are promising candidates for optoelectronic neuromorphic electronic components owing to their advantages from both material and signal perspectives. Organic materials have advantages such as low cost, tunable properties according to the molecular design, mechanical flexibility, and biocompatibility. In addition, using light as an input signal affords advantages such as ultrafast signal transmission speed, wide bandwidth, and wireless communication. Thus, different types of organic photonic synapses have been researched using various mechanisms and new materials. In this review, we first introduce the biological synaptic properties imitated by photonic synapses. Next, the operating mechanism and materials used are discussed by categorizing the device structures into two-terminal and three-terminal devices. To verify the applicability of organic photonic synapses in the real world, we present various applications such as pattern recognition, smart windows, and Pavlov’s dog experiment, which have been demonstrated in previous studies. Finally, we discuss the remaining challenges and provide directions for further research on organic photonic synapses.

Axial N Ligand-Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single-Atoms Nanozymes.

Learning and studying the structure-activity relationship in the bio-enzymes is conducive to the design of nanozymes for energy and environmental application. Herein, Fe single-atom nanozymes (Fe-SANs) with Fe-N5 site, inspired by the structure of cytochromes P450 (CYPs), are developed and characterized. Similar to the CYPs, the hyperoxide can activate the Fe(III) center of Fe-SANs to generate Fe(IV)O intermediately, which can transfer oxygen to the substrate with ultrafast speed. Particularly, using the peroxymonosulfate (PMS)-activated Fe-SANs to oxidize sulfamethoxazole, a typical antibiotic contaminant, as the model hyperoxides activation reaction, the excellent activity within 284 min-1 g-1 (catalyst) mmol-1 (PMS) oxidation rate and 91.6% selectivity to the Fe(IV)O intermediate oxidation are demonstrated. More importantly, instead of promoting PMS adsorption, the axial N ligand modulates the electron structure of FeN5 SANs for the lower reaction energy barrier and promotes electron transfer to PMS to produce Fe(IV)O intermediate with high selectivity. The highlight of the axial N coordination in the nanozymes in this work provides deep insight to guide the design and development of nanozymes nearly to the bio-enzyme with excellent activity and selectivity.

Ultrafast Self-propelling directionally water transporting wood via cell wall reshaping for water manipulation

Water-transport based on biomimetic self-propelled directional water transport materials have attracted wide attention but are limited by low transport speed, costly and complicated preparation, and scaling difficulty. By retaining native cellulose microfibril structure within wood cell walls and their controlled shrinkage, we constructed a self-propelling directionally water transporting wood (SDTW) by reshaping the cell wall to generate robust capillary forces due to aligned longitudinal hierarchical wood cell structures. Hierarchical structures containing directional parallel macro- and micro-sized ridge-groove structures and creating nano-voids are fabricated. They are further intactly fixed after reaction with maleic anhydride to improve the dimensional stability and environmental durability without changing the hydrophilicity on surface. Resulting SDTW exhibited an ultrafast water transport speed of 200.4 mm/s (∼260 % of Nepenthes alata showing a fast speed of 78 mm/s as a native structure) and water absorbing rate of 1.15 × 105 L/m2/h (over 4200-fold higher than that of natural wood). With these ultrafast water transport characters, SDTW was used as water manipulating systems for fast bottom to up transportation of liquid water at a rate of 193.5 mm/s, and as high fog harvesting system with an efficiency of 10.6 g/cm2/h. With its facility, durability, scalability, and sustainability, the SDTW demonstrates a new class of sustainable wood-based materials for practical water manipulation applications.

Reconfigurable matrix multiplier with on-site reinforcement learning.

Matrix multiplication is a fundamental building block for modern information processing and artificial intelligence algorithms. Photonics-based matrix multipliers have recently attracted much attention due to their advantages of low energy and ultrafast speed. Conventionally, achieving matrix multiplication relies on bulky Fourier optical components, and the functionalities are unchangeable once the design is determined. Furthermore, the bottom-up design strategy cannot easily be generalized into concrete and practical guidelines. Here, we introduce a reconfigurable matrix multiplier driven by on-site reinforcement learning. The constituent transmissive metasurfaces incorporating varactor diodes serve as tunable dielectrics based on the effective medium theory. We validate the viability of tunable dielectrics and demonstrate the performance of matrix customization. This work represents a new avenue in realizing reconfigurable photonic matrix multipliers for on-site applications.

High Performing Solid‐State Organic Electrochemical Transistors Enabled by Glycolated Polythiophene and Ion‐Gel Electrolyte with a Wide Operation Temperature Range from −50 to 110 °C

AbstractThe development of organic electrochemical transistors (OECTs) capable of maintaining their high amplification, fast transient speed, and operational stability in harsh environments will advance the growth of next‐generation wearable and biological electronics. In this study, a high‐performance solid‐state OECT (SSOECT) is successfully demonstrated, showing a recorded high transconductance of 220 ± 59 S cm−1, ultrafast device speed of ≈10 kHz with excellent operational stability over 10 000 switching cycles, and thermally stable under a wide temperature range from −50 to 110 °C. The developed SSOECTs are successfully used to detect low‐amplitude physiological signals, showing a high signal‐to‐noise‐ratio of 32.5 ± 2.1 dB. For the first time, the amplifying power of these SSOECTs is also retained and reliably shown to collect high‐quality electrophysiological signals even under harsh temperatures (−50 and 110 °C). The demonstration of high‐performing SSOECTs and its application in harsh environment are core steps toward their implementation in next‐generation wearable electronics and bioelectronics.

Realizing ultrahigh breakdown strength and ultrafast discharge speed in novel barium titanate-based ceramics through multicomponent compounding strategy

Lead-free dielectric ceramics have been an important segment in the energy storage field. In this work, a synergistic optimization strategy of multicomponent compounding involving 0.9[0.88Ba1-xCaxTiO3-0.12Bi(Mg2/3(Nb0.85Ta0.15)1/3)O3]− 0.1Bi0.5Na0.5TiO3 (B1-xCxT-BMNT-BNT) ceramics were proposed. With the increase of Ca2+ content (x), the content of the CaTiO3 phase increases, which obviously enhances the breakdown strength (BDS) and energy storage properties. The optimal energy storage performances were obtained in the B0.6C0.4T-BMNT-BNT ceramic, showing a large recoverable energy density (Wrec) of 3.59 J/cm3 and ultrahigh efficiency (η) of 90.86% at 430 kV/cm. Meanwhile, the B0.6C0.4T-BMNT-BNT material also exhibits good temperature stability (20–180°C), frequency stability (1–500 Hz) and fatigue resistant (1–105 cycles). In addition, the B0.6C0.4T-BMNT-BNT ceramic also possesses ultrafast discharge time (t0.9 = 38.6 ns) in the charge and discharge test. The above merits make the B0.6C0.4T-BMNT-BNT ceramic a promising candidate for wide-temperature dielectric capacitors in pulse power applications.

Wafer-scale synthesis of wide bandgap 2D GeSe2 layers for self-powered ultrasensitive UV photodetection and imaging

Emerging wide-bandgap 2D GeSe2 has been considered as a promising candidate for next-generation ultraviolet (UV) imaging systems, which typically require miniaturization, high stability, and self-powered sensing capability. Nevertheless, the lack of reliable wafer-scale synthesis strategies remains a major obstacle to unleashing its full device potential. Herein, we report the synthesis of inch-level 2D GeSe2 layers with precise layer control and customized patterns via a facile post-annealing approach, which reveals a layer-independent direct bandgap of ∼3.0 eV. Moreover, high-quality GeSe2/GaN mixed-dimensional van der Waals heterojunctions fabricated via in-situ growth mode display an ultrasensitive self-powered UV photoresponse with a UV-to-visible rejection ratio of 1.8 × 105, a large responsivity of 261.7 mA/W, a high specific detectivity of 1.24 × 1014 Jones, as well as an ultrafast response speed to track nanosecond pulsed UV signals. In particular, the photodetector could sense ultraweak UV signals with a minimum detection limit of 180 pW/cm2 at 360 nm. Besides, the large-area growth of GeSe2 enables the implementation of integrated photodiode arrays for the self-powered image sensor, demonstrating the great promise of 2D GeSe2 for high-sensitivity UV detection and imaging.

Thermal and infrared light self-repairing, high sensitivity, and large strain sensing range shape memory MXene/CNTs/EVA composites fiber strain sensor for human motion monitoring

Wearable electronic gadgets have always been in great demand for multifunctional flexible strain sensors. However, developing a flexible strain sensor with excellent characteristics such as high sensitivity, wide sensing range, and excellent durability continues to be a significant challenge. On the one hand, the two-performance metrics of high sensitivity and wide sensing range are mutually exclusive, because the former requires significant structural changes under small strains, whereas the latter necessitates the preservation of morphological integrity under large deformations. On the other hand, the usage of flexible strain sensors is invariably accompanied by the destruction of the conductive network, rendering the device unusable for an extended period of time. Here, based on the unique strain related microcrack structure of the Ti 3 C 2 T x (MXene)/carbon nanotubes (CNTs) synergistic interaction and the shape memory property of ethylene vinyl acetate polymer (EVA), a MXene/CNTs/EVA fiber strain sensor was innovatively designed and prepared by swelling ultrasonic method. The results showed that the sensor combines a large strain sensing range (190%), high sensitivity (82.5), ultra-fast response speed (178.9 ms), and excellent durability and stability (> 10,000 cycles). What is even more exciting is that if the strain sensor is failure, it can be repaired by heating for 2 min or infrared irradiation for 5.4 s, and the mechanical and electrical properties of the repaired sensor can be restored to 92% and 94% of the original. In addition, this strain sensor can accurately monitor subtle and large movements of the human body (including elbow and finger bending, speaking, and mouth opening/closing), even if the damaged MXene/CNTs/EVA fiber strain sensor has been repaired. The self-repairing MXene/CNTs/EVA composites fiber-based shape memory matrix has excellent potential as a wearable strain sensor. • The MXene/CNTs/EVA fiber strain sensors exhibit excellent elasticity, and electrical conductivity. • The fiber strain sensors have wide strain sensing range, high sensitivity, and high stability. • The fiber strain sensors can be repaired by heating and infrared light irradiation. • The fiber strain sensors can detect a wide range of human motion and weak physiological signals.

Optical Control of High-Harmonic Generation at the Atomic Thickness.

High-harmonic generation (HHG), an extreme nonlinear optical phenomenon beyond the perturbation regime, is of great significance for various potential applications, such as high-energy ultrashort pulse generation with outstanding spatiotemporal coherence. However, efficient active control of HHG is still challenging due to the weak light-matter interaction displayed by currently known materials. Here, we demonstrate optically controlled HHG in monolayer semiconductors via the engineering of interband polarization. We find that HHG can be efficiently controlled in the excitonic spectral region with modulation depths up to 95% and ultrafast response speeds of several picoseconds. Quantitative time-domain theory of the nonlinear optical susceptibilities in monolayer semiconductors further corroborates these experimental observations. Our demonstration not only offers an in-depth understanding of HHG but also provides an effective approach toward active optical devices for strong-field physics and extreme nonlinear optics.

Ultrafast perturbation of magnetic domains by optical pumping in a ferromagnetic multilayer

Ultrafast optical pumping of spatially nonuniform magnetic textures is known to induce far-from-equilibrium spin transport effects. Here, we use ultrafast x-ray diffraction with unprecedented dynamic range to study the laser-induced dynamics of labyrinth domain networks in ferromagnetic CoFe/Ni multilayers. We detected azimuthally isotropic, odd order, magnetic diffraction rings up to fifth order. The amplitudes of all three diffraction rings quench to different degrees within 1.6 ps. In addition, all three of the detected diffraction rings both broaden by 15% and radially contract by 6% during the quench process. We are able to rigorously quantify a 31% ultrafast broadening of the domain walls via Fourier analysis of the order-dependent quenching of the three detected diffraction rings. The broadening of the diffraction rings is interpreted as a reduction in the domain coherence length, but the shift in the ring radius, while unambiguous in its occurrence, remains unexplained. In particular, we demonstrate that a radial shift explained by domain-wall broadening can be ruled out. With the unprecedented dynamic range of our data, our results provide convincing evidence that labyrinth domain structures are spatially perturbed at ultrafast speeds under far-from-equilibrium conditions, albeit the mechanism inducing the perturbations remains yet to be clarified.7 MoreReceived 15 June 2022Revised 15 September 2022Accepted 26 September 2022DOI:https://doi.org/10.1103/PhysRevB.106.144422©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDomain wallsMagnetic domainsMagnetic textureMagnetismMagnetization dynamicsUltrafast demagnetizationUltrafast magnetic effectsUltrafast magnetization dynamicsCondensed Matter, Materials & Applied Physics

Self‐Driven Ultrafast Response Photodetector Based on Graphene/Water/Silicon Structure

The graphene/water/semiconductor structure can convert kinetic energy into direct current output using the polarization principle, showing its unique physical characteristics and superior performance in the power generation direction. Herein, a photodetector application is developed based on the structure and reveals the physical mechanism of the displacement current caused by the polarization of more water molecules induced by silicon upon excitation under illumination. Furthermore, the research uses a graphene/water/silicon heterojunction as a self‐driven photodetector with a wide response band contains from ultraviolet to visible light, the photodetector has a high sensitivity to the incident light of 635 nm with a responsivity of 433.46 mA W−1 and detectivity as 1.57 × 1012 Jones. Moreover, the photodetector based on graphene–water–Si has an ultrafast response speed, with a typical rise/fall time of 564/766 ns. The photodetector remains substantial stable while sealed with polymethyl methacrylate after storage in air for 1 month. These results imply that graphene/water/silicon heterojunctions may have great potential for practical applications as high‐performance self‐driven photodetectors.

AutoNanopore: An Automated Adaptive and Robust Method to Locate Translocation Events in Solid-State Nanopore Current Traces.

Solid-state nanopore sequencing has shown impressive performances in several research scenarios but is still challenging, mainly due to the ultrafast speed of DNA translocation and significant noises embedded in raw signals. Hence, event detection, aiming to locate precisely these translocation events, is the fundamental step of data analysis. However, existing event detection methods use either a user-defined global threshold or an adaptive threshold determined by the data, assuming the baseline current to be stable over time. These disadvantages limit their applications in real-world application scenarios, especially considering that the results of different methods are often inconsistent. In this study, we develop an automated adaptive method called AutoNanopore, for fast and accurate event detection in current traces. The method consists of three consecutive steps: current trace segmentation, current amplitude outlier identification by straightforward statistical analyses, and event characterization. Then we propose ideas/metrics on how to quantitatively evaluate the performance of an event detection method, followed by comparing the performance of AutoNanopore against two state-of-the-art methods, OpenNanopore and EventPro. Finally, we examine if one method can detect the overlapping events detected by the other two, demonstrating that AutoNanopore has the highest coverage ratio. Moreover, AutoNanopore also performs well in detecting challenging events: e.g., those with significantly varying baselines.

(Invited) From Bulk to Nanostructured Perovskites

The dimensionality of semiconductors has a crucial role in determining their properties. Recently, metal halide perovskites have been demonstrated with many exciting applications, attracting wide attention to further their development for advanced optoelectronics, such as photovoltaics, photodetectors, light-emitting diodes, and lasers. At length scales down to nanoscale regimes, surface features as well as quantum confinement effects become dominant in regulating the material properties of perovskite materials. In past years, our group focus on the synthesis and characterization of metal halide perovskites with different configurations, ranging from bulk films, microplates, nanosheets, to nanowires. The corresponding physical properties and device applications were also systematically studied based on their widely tunable dimensionality, morphologies, and compositions.Specifically, for perovskite bulk films, surface defects and bulk structural order significantly affect their device performance. Through optimizing processing techniques, self-assembled quasi-2D perovskite films with graded phase distribution were successfully prepared. Gradient type-II band alignments along the out-of-plane direction of perovskites with spontaneous separation of photo-generated electrons and holes are obtained, which is later employed to construct self-powered vertical-structure photodetectors for the first time. Without any driving voltage, the device exhibited impressive performance with the responsivity up to 444 mA/W and ultrashort response time down to 52 µs. In addition, to assess the intrinsic material properties of crystalline perovskites, freestanding MAPbI3 nanosheets and lead-free Cs3Sb2I9 microplates were fabricated by two-step chemical vapor deposition method, in which excellent optoelectronic performance (e.g., responsively of MAPbI3 nanosheet is measured to be 40 A/W) together with ultra-fast response speed (down to 58 µs) and superior thermal stability were obtained.For nanostructured perovskites, understanding the dimensional features and their impact on the materials and devices is becoming increasingly important. Lately, we reported the direct vapor-liquid-solid growth of single-crystalline all-inorganic lead halide perovskite (i.e., CsPbX3; X = Cl, Br, or I) NWs. These NWs exhibited high-performance photodetection with the responsivity exceeding 4489 A/W and detectivity over 7.9 × 1012 Jones toward the visible light regime. Field-effect transistors based on individual CsPbX3 NWs were also fabricated to show the impressive carrier mobility of 3.05 cm2/Vs, being higher than other all-inorganic perovskite devices. Besides, the realization of high-mobility CsPbBr3 NW devices is reported via a simple surface charge transfer doping strategy. After MoO3 decoration and device fabrication, the hole mobility of CsPbBr3/MoO3 core-shell NW device is significantly enhanced to 23.3 cm2/Vs. All these results provide important guidelines for the further improvement of these perovskite nanostructures for practical utilization.

Achieving Ultrahigh Energy-Storage Density with Excellent Thermal Stability in Sr0.7Bi0.2TiO3-Based Relaxors via Polarization Behavior Modulation.

Dielectric capacitors possessing the inherent superiorities of high power density and ultrafast charge-discharge speed make their utilization in energy-storage devices extremely propitious, although the relatively low recoverable energy-storage density (Wrec) may impede their applications. In this work, unlike the mainstream approach of destroying long-range ferroelectric/antiferroelectric order and inducing relaxor properties to achieve a high Wrec value, we have selected end members with a high polarization gene to promote the polarization behavior of the typical relaxor Sr0.7Bi0.2TiO3. Therefore, an ultrahigh Wrec ∼ 8 J/cm3 and a superior efficiency (η) ∼ 91% are accomplished in the 0.98[0.56(Sr0.7Bi0.2)TiO3-0.44(Bi0.5Na0.5)TiO3]-0.02 Bi(Mg0.5Ti0.5)O3 sample. The achieved Wrec value is record high in Sr0.7Bi0.2TiO3-based systems as far as we know. The polarization-enhancement behavior can be explained by the phase field simulation results, phase content variance in X-ray diffraction Rietveld refinement, hardening trend in Raman spectroscopy, domain morphology, and local symmetry in transmission electron microscope analysis. Meanwhile, the ceramic possesses excellent thermal stability (ΔWrec < 12.7% and Δη < 10.4%, -50-200 °C), frequency (ΔWrec < 2.69% and Δη < 2.06%, 0.5-500 Hz), and fatigue-resistant stability (ΔWrec < 0.08% and Δη < 0.2%, up to 1 × 105 cycles). Accordingly, this work proposes a design idea to tailor the polarization behavior and energy-storage properties of typical relaxors.