Showing papers on "Nanowire published in 2017"

Enhancing ionic conductivity in composite polymer electrolytes with well-aligned ceramic nanowires

Abstract: In contrast to conventional organic liquid electrolytes that have leakage, flammability and chemical stability issues, solid electrolytes are widely considered as a promising candidate for the development of next-generation safe lithium-ion batteries. In solid polymer electrolytes that contain polymers and lithium salts, inorganic nanoparticles are often used as fillers to improve electrochemical performance, structure stability, and mechanical strength. However, such composite polymer electrolytes generally have low ionic conductivity. Here we report that a composite polymer electrolyte with well-aligned inorganic Li+-conductive nanowires exhibits an ionic conductivity of 6.05 × 10−5 S cm-1 at 30 ∘C, which is one order of magnitude higher than previous polymer electrolytes with randomly aligned nanowires. The large conductivity enhancement is ascribed to a fast ion-conducting pathway without crossing junctions on the surfaces of the aligned nanowires. Moreover, the long-term structural stability of the polymer electrolyte is also improved by the use of nanowires. Fast ionic conductivity of solid electrolytes is a must in the development of next-generation solid-electrolyte-based lithium-ion batteries. Here the authors report that composite polymer electrolytes with well-aligned inorganic nanowires can achieve much larger conductivities than those without.

Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures

Abstract: The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals that are based on the transient flow of electrons in an external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity of up to 9.4 × 10–3 kPa–1 and a fast response time down to 5–7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

Earth Abundant Fe/Mn-Based Layered Oxide Interconnected Nanowires for Advanced K-Ion Full Batteries.

Abstract: K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of K precursor materials. However, the main challenge lies on the lack of stable materials to accommodate the intercalation of large-size K-ions. Here we designed and constructed a novel earth abundant Fe/Mn-based layered oxide interconnected nanowires as a cathode in KIBs for the first time, which exhibits both high capacity and good cycling stability. On the basis of advanced in situ X-ray diffraction analysis and electrochemical characterization, we confirm that interconnected K0.7Fe0.5Mn0.5O2 nanowires can provide stable framework structure, fast K-ion diffusion channels, and three-dimensional electron transport network during the depotassiation/potassiation processes. As a result, a considerable initial discharge capacity of 178 mAh g–1 is achieved when measured for KIBs. Besides, K-ion full batteries based on interconnected K0.7Fe0.5Mn0.5O2 nanowires/soft carbon are assembled...

Nanolattices: An Emerging Class of Mechanical Metamaterials.

Abstract: In 1903, Alexander Graham Bell developed a design principle to generate lightweight, mechanically robust lattice structures based on triangular cells; this has since found broad application in lightweight design. Over one hundred years later, the same principle is being used in the fabrication of nanolattice materials, namely lattice structures composed of nanoscale constituents. Taking advantage of the size-dependent properties typical of nanoparticles, nanowires, and thin films, nanolattices redefine the limits of the accessible material-property space throughout different disciplines. Herein, the exceptional mechanical performance of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics is examined. The efficient integration of architecture and size-affected properties is key to further develop nanolattices. The introduction of a hierarchical architecture is an effective tool in enhancing mechanical properties, and the eventual goal of nanolattice design may be to replicate the intricate hierarchies and functionalities observed in biological materials. Additive manufacturing and self-assembly techniques enable lattice design at the nanoscale; the scaling-up of nanolattice fabrication is currently the major challenge to their widespread use in technological applications.

One-dimensional CdS@MoS2 core-shell nanowires for boosted photocatalytic hydrogen evolution under visible light

Abstract: The well-defined one-dimensional (1D) CdS@MoS2 (CM) core-shell nanowires are constructed by employing CdS nanowires (CdS NWs) as nanobuilding blocks via a facile hydrothermal strategy. The synergistic interaction, stemming from the large and intimate coaxial interfacial contact between MoS2 thin shell and 1D CdS core, can efficiently retard the charge carrier recombination and the MoS2 as noble-metal-free cocatalyst enriches the active sites for H2 evolution from water. Consequently, in comparison to bare CdS nanowires, the resultant 1D core-shell CM composite exhibits distinctly enhanced visible light activity for the evolution of H2. Notably, the activity of 1D CM with the optimized 2 wt% of MoS2 exceeds that of pure CdS and CdS–1 wt% Pt composite by a factor of 64 and 4 times, respectively, under identical reaction conditions, while the apparent quantum yield (A.Q.Y.) at 420 nm over 1D CM reaches 28.5%. This work provides a simple paradigm for facile and finely controlled synthesis of well-shaped 1D-based composite photocatalysts towards boosted solar energy conversion.

Peapod-like Li3VO4/N-Doped Carbon Nanowires with Pseudocapacitive Properties as Advanced Materials for High-Energy Lithium-Ion Capacitors

Abstract: Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double-layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li3 VO4 with low Li-ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N-doped carbon-encapsulated Li3 VO4 nanowires are synthesized through a morphology-inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g-1 at 0.1 A g-1 , excellent rate capability, and long-term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge-transfer, the Li3 VO4 /N-doped carbon nanowires exhibit a high-rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li3 VO4 /N-doped carbon nanowires delivers a high energy density of 136.4 Wh kg-1 at a power density of 532 W kg-1 , revealing the potential for application in high-performance and long life energy storage devices.

Flexible and Thermostable Graphene/SiC Nanowire Foam Composites with Tunable Electromagnetic Wave Absorption Properties.

Abstract: Three-dimensional (3D) flexible foams consisting of reduced graphene oxides (rGO) and in situ grown SiC nanowires (NWs) were prepared using freeze-drying and carbothermal reduction processes. By means of incorporating SiC nanowires into rGO foams, both the thermostability and electromagnetic absorption of the composites were improved. It was demonstrated that rGO/SiC NW foams were thermostable beyond ∼630 °C (90% weight retention in air atmosphere). As expected, rGO/SiC NW foams in the poly(dimethylsiloxane) matrix achieved effective absorption in the entire X-band (8.2–12.4 GHz) with a thinner thickness (3 mm) in comparison with those of the pure rGO foams. It is revealed that SiC nanowires with abundant stacking faults, twinning interfaces, and bridged junctions play an important role in the enhanced electromagnetic absorption performance, in addition to the contribution of interconnected graphene networks. Hierarchical rGO/SiC NW foams not only are efficient absorbers in the critical environments but a...

Epitaxy of advanced nanowire quantum devices

Abstract: Semiconductor nanowires are ideal for realizing various low-dimensional quantum devices. In particular, topological phases of matter hosting non-Abelian quasiparticles (such as anyons) can emerge when a semiconductor nanowire with strong spin-orbit coupling is brought into contact with a superconductor. To exploit the potential of non-Abelian anyons - which are key elements of topological quantum computing - fully, they need to be exchanged in a well-controlled braiding operation. Essential hardware for braiding is a network of crystalline nanowires coupled to superconducting islands. Here we demonstrate a technique for generic bottom-up synthesis of complex quantum devices with a special focus on nanowire networks with a predefined number of superconducting islands. Structural analysis confirms the high crystalline quality of the nanowire junctions, as well as an epitaxial superconductor-semiconductor interface. Quantum transport measurements of nanowire 'hashtags' reveal Aharonov-Bohm and weak-antilocalization effects, indicating a phase-coherent system with strong spin-orbit coupling. In addition, a proximity-induced hard superconducting gap (with vanishing sub-gap conductance) is demonstrated in these hybrid superconductor-semiconductor nanowires, highlighting the successful materials development necessary for a first braiding experiment. Our approach opens up new avenues for the realization of epitaxial three-dimensional quantum architectures which have the potential to become key components of various quantum devices.

Solvothermal Synthesis of High-Quality All-Inorganic Cesium Lead Halide Perovskite Nanocrystals: From Nanocube to Ultrathin Nanowire

Abstract: Recently, all-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals have drawn much attention because of their outstanding photophysical properties and potential applications. In this work, a simple and efficient solvothermal approach to prepare CsPbX3 nanocrystals with tunable and bright photoluminescent (PL) properties, controllable composition, and morphology is presented. CsPbX3 nanocubes are successfully prepared with bright emission high PL quantum yield up to 80% covering the full visible range and narrow emission line widths (from 12 to 36 nm). More importantly, ultrathin CsPbX3 (X = Cl/Br, Br, and Br/I) nanowires (with diameter as small as ≈2.6 nm) can be prepared in a very high morphological yield (almost 100%). A strong quantum confinement effect is observed in the ultrathin nanowires, in which both the absorption and emission peaks shift to shorter wavelength range compared to their bulk bandgap. The reaction parameters, such as temperature and precursors, are varied to investigate the growth process. A white light-emitting device prototype device with wide color gamut covering up to 120% of the National Television System Committee standard has been demonstrated by using CsPbBr3 nanocrystals as the green light source. The method in this study provides a simple and efficient way to prepare high-quality CsPbX3 nanocrystals.

In Situ Growth of Core–Sheath Heterostructural SiC Nanowire Arrays on Carbon Fibers and Enhanced Electromagnetic Wave Absorption Performance

Abstract: Large-scale core–sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core–sheath heterostructural SiC nanowires (SiCnws) were discussed in detail. The SiCnws-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of −45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiCnws-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of −50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiCnws-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.

Wrapping Aligned Carbon Nanotube Composite Sheets around Vanadium Nitride Nanowire Arrays for Asymmetric Coaxial Fiber-Shaped Supercapacitors with Ultrahigh Energy Density

Abstract: The emergence of fiber-shaped supercapacitors (FSSs) has led to a revolution in portable and wearable electronic devices. However, obtaining high energy density FSSs for practical applications is still a key challenge. This article exhibits a facile and effective approach to directly grow well-aligned three-dimensional vanadium nitride (VN) nanowire arrays (NWAs) on carbon nanotube (CNT) fiber with an ultrahigh specific capacitance of 715 mF/cm2 in a three-electrode system. Benefiting from their intriguing structural features, we successfully fabricated a prototype asymmetric coaxial FSS (ACFSS) with a maximum operating voltage of 1.8 V. From core to shell, this ACFSS consists of a CNT fiber core coated with VN@C NWAs as the negative electrode, Na2SO4 poly(vinyl alcohol) (PVA) as the solid electrolyte, and MnO2/conducting polymer/CNT sheets as the positive electrode. The novel coaxial architecture not only fully enables utilization of the effective surface area and decreases the contact resistance between...

Seamlessly Conductive 3D Nanoarchitecture of Core–Shell Ni-Co Nanowire Network for Highly Efficient Oxygen Evolution

Abstract: Electrochemical splitting of water is an attractive way to produce hydrogen fuel as a clean and renewable energy source. However, a major challenge is to accelerate the sluggish kinetics of the anodic half-cell reaction where oxygen evolution reaction (OER) takes place. Here, a seamlessly conductive 3D architecture is reported with a carbon-shelled Ni-Co nanowire network as a highly efficient OER electrocatalyst. Highly porous and granular Ni-Co nanowires are first grown on a carbon fiber woven fabric utilizing a cost-effective hydrothermal method and then conductive carbon shell is coated on the Ni-Co nanowires via glucose carbonization and annealing processes. The conductive carbon layer surrounding the nanowires is introduced to provide a continuous pathway for facile electron transport throughout the whole of the integrated 3D catalyst. This 3D hierarchical structure provides several synergistic effects and beneficial functions including a large number of active sites, easy accessibility of water, fast electron transport, rapid release of oxygen gas, enhanced electrochemical durability, and stronger structural integrity, resulting in a remarkable OER activity that delivers an overpotential of 302 mV with a Tafel slope of 43.6 mV dec−1 at a current density of 10 mA cm−2 in an alkaline medium electrolyte (1 m KOH).

Achieving Remarkable Activity and Durability toward Oxygen Reduction Reaction Based on Ultrathin Rh-Doped Pt Nanowires

Abstract: The research of active and sustainable electrocatalysts toward oxygen reduction reaction (ORR) is of great importance for industrial application of fuel cells Here, we report a remarkable ORR catalyst with both excellent mass activity and durability based on sub 2 nm thick Rh-doped Pt nanowires, which combine the merits of high utilization efficiency of Pt atoms, anisotropic one-dimensional nanostructure, and doping of Rh atoms Compared with commercial Pt/C catalyst, the Rh-doped Pt nanowires/C catalyst shows a 78 and 54-fold enhancement in mass activity and specific activity, respectively The combination of extended X-ray absorption fine structure analysis and density functional theory calculations reveals that the compressive strain and ligand effect in Rh-doped Pt nanowires optimize the adsorption energy of hydroxyl and in turn enhance the specific activity Moreover, even after 10000 cycles of accelerated durability test in O2 condition, the Rh-doped Pt nanowires/C catalyst exhibits a drop of 92

Advances in Small Perovskite-Based Lasers

Abstract: Lead halide perovskites have recently become a rapidly growing research field due to their great potential in next-generation solar cells and photonic sources. As a direct bandgap semiconductor, perovskites are also promising candidates for low-threshold and multicolor lasing devices due to their high optical gain, ease of bandgap engineering, large absorption coefficient, and low defect state density. In particular, reduced-dimensional perovskite structures including nanoplatelets, nanowires, and quantum dots, are crucial for the development of micro- or nanosized laser sources for optical chips and high-resolution imaging, etc. Here, perovskite nanophotonics, in particular the lasing properties of perovskite nanostructures, are discussed. The rapid advances of small lasers based on perovskite nanostructures using both active and passive microcavities are reviewed; these are mainly classified into four sections: thin films, nanoplatelets, nanowires, and quantum dots. Lasing performance in terms of threshold, color-tunability, spectral coherence, and stability is introduced from both materials and microcavity respects. Fundamental photophysical mechanisms involved in the photoluminescence lasing process, from absorption, emission to gain, are discussed in order to provide insightful understanding lasing properties of different types of perovskites. Finally, some future prospects for perovskite lasing devices are provided.

Three-dimensional NiCo2O4@NiWO4 core–shell nanowire arrays for high performance supercapacitors

Abstract: Hierarchical NiCo2O4@NiWO4 core–shell nanowire arrays supported on nickel foam have been synthesized via a facile hydrothermal route coupled with a post-thermal treatment. The hydrothermally synthesized NiCo2O4 nanowire arrays serve as the scaffold for anchoring the NiWO4 nanosheets. When evaluated as binder-free electrodes for supercapacitors, the optimized NiCo2O4@NiWO4 hybrid electrode demonstrates remarkable electrochemical performance with a high specific capacitance of 1384 F g−1 at a current density of 1 A g−1 and superior cycling stability (87.6% retention over 6000 cycles at a current density of 5 A g−1). In addition, an asymmetric supercapacitor (ASC) based on the optimized NiCo2O4@NiWO4 electrode and activated carbon is assembled with 6 M KOH as the electrolyte. The as-fabricated ASC device can achieve a maximum high energy density of 41.5 W h kg−1 at a power density of 760 W kg−1. The excellent supercapacitive performance could be ascribed to the unique core–shell architecture and the synergistic effect from the NiCo2O4 nanowires and the ultrathin NiWO4 nanosheets.

Percolating Network of Ultrathin Gold Nanowires and Silver Nanowires toward “Invisible” Wearable Sensors for Detecting Emotional Expression and Apexcardiogram

Abstract: 2 nm thin gold nanowires (AuNWs) have extremely high aspect ratio (≈10 000) and are nanoscale soft building blocks; this is different from conventional silver nanowires (AgNWs), which are more rigid. Here, highly sensitive, stretchable, patchable, and transparent strain sensors are fabricated based on the hybrid films of soft/hard networks. They are mechanically stretchable, optically transparent, and electrically conductive and are fabricated using a simple and cost-effective solution process. The combination of soft and more rigid nanowires enables their use as high-performance strain sensors with the maximum gauge factor (GF) of ≈236 at low strain (<5%), the highest stretchability of up to 70% strain, and the optical transparency is from 58.7% to 66.7% depending on the amount of the AuNW component. The sensors can detect strain as low as 0.05% and are energy efficient to operate at a voltage as low as 0.1 V. These attributes are difficult to achieve with a single component of either AuNWs or AgNWs. The outstanding sensing performance indicates their potential applications as “invisible” wearable sensors for biometric information collection, as demonstrated in applications for detecting facial expressions, respiration, and apexcardiogram.

Vapor-Phase Epitaxial Growth of Aligned Nanowire Networks of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I)

Abstract: With the intense interest in inorganic cesium lead halide perovskites and their nanostructures for optoelectronic applications, high-quality crystalline nanomaterials with controllable morphologies and growth directions are desirable. Here, we report a vapor-phase epitaxial growth of horizontal single-crystal CsPbX3 (X = Cl, Br, I) nanowires (NWs) and microwires (MWs) with controlled crystallographic orientations on the (001) plane of phlogopite and muscovite mica. Moreover, single NWs, Y-shaped branches, interconnected NW or MW networks with 6-fold symmetry, and, eventually, highly dense epitaxial network of CsPbBr3 with nearly continuous coverage were controllably obtained by varying the growth time. Detailed structural study revealed that the CsPbBr3 wires grow along the [001] directions and have the (100) facets exposed. The incommensurate heteroepitaxial lattice match between the CsPbBr3 and mica crystal structures and the growth mechanism of these horizontal wires due to asymmetric lattice mismatch ...

Directional Growth of Ultralong CsPbBr3 Perovskite Nanowires for High-Performance Photodetectors

Abstract: Directional growth of ultralong nanowires (NWs) is significant for practical application of large-scale optoelectronic integration. Here, we demonstrate the controlled growth of in-plane directional perovskite CsPbBr3 NWs, induced by graphoepitaxial effect on annealed M-plane sapphire substrates. The wires have a diameter of several hundred nanometers, with lengths up to several millimeters. Microstructure characterization shows that CsPbBr3 NWs are high-quality single crystals, with smooth surfaces and well-defined cross section. The NWs have very strong band-edge photoluminescence (PL) with a long PL lifetime of ∼25 ns and can realize high-quality optical waveguides. Photodetectors constructed on these individual NWs exhibit excellent photoresponse with an ultrahigh responsivity of 4400 A/W and a very fast response speed of 252 μs. This work presents an important step toward scalable growth of high-quality perovskite NWs, which will provide promising opportunities in constructing integrated nanophotonic...

Zero-Energy Modes from Coalescing Andreev States in a Two-Dimensional Semiconductor-Superconductor Hybrid Platform.

Abstract: We investigate zero-bias conductance peaks that arise from coalescing subgap Andreev states, consistent with emerging Majorana zero modes, in hybrid semiconductor-superconductor wires defined in a two-dimensional $\mathrm{InAs}/\mathrm{Al}$ heterostructure using top-down lithography and gating. The measurements indicate a hard superconducting gap, ballistic tunneling contact, and in-plane critical fields up to 3 T. Top-down lithography allows complex geometries, branched structures, and straightforward scaling to multicomponent devices compared to structures made from assembled nanowires.

Organic–Inorganic Hybrid Perovskite Nanowire Laser Arrays

Abstract: Fabrication of semiconductor nanowire laser arrays is very challenging, owing to difficulties in direct monolithic growth and patterning of III–V semiconductors on silicon substrates Recently, methylammonium lead halide perovskites (MAPbX3, X = Cl, Br, I) have emerged as an important class of high-performance solution-processed optoelectronic materials Here, we combined the “top–down” fabricated polydimethylsiloxane rectangular groove template (RGT) with the “bottom-up” solution self-assembly together to prepare large-scale perovskite nanowire (PNW) arrays The template confinement effect led to the directional growth of MAPbX3 along RGTs into PNWs We achieved precise control over not only the dimensions of individual PNWs (width 460–2500 nm; height 80–1000 nm, and length 10–50 μm) but also the interwire distances Well-defined dimensions and uniform geometries enabled individual PNWs to function as high-quality Fabry–Perot nanolasers with almost identical optical modes and similarly low-lasing thresho

From Precursor Powders to CsPbX3 Perovskite Nanowires: One-Pot Synthesis, Growth Mechanism, and Oriented Self-Assembly

Abstract: The colloidal synthesis and assembly of semiconductor nanowires continues to attract a great deal of interest. Herein, we describe the single-step ligand-mediated synthesis of single-crystalline CsPbBr3 perovskite nanowires (NWs) directly from the precursor powders. Studies of the reaction process and the morphological evolution revealed that the initially formed CsPbBr3 nanocubes are transformed into NWs through an oriented-attachment mechanism. The optical properties of the NWs can be tuned across the entire visible range by varying the halide (Cl, Br, and I) composition through subsequent halide ion exchange. Single-particle studies showed that these NWs exhibit strongly polarized emission with a polarization anisotropy of 0.36. More importantly, the NWs can self-assemble in a quasi-oriented fashion at an air/liquid interface. This process should also be easily applicable to perovskite nanocrystals of different morphologies for their integration into nanoscale optoelectronic devices.

Large Area Co-Assembly of Nanowires for Flexible Transparent Smart Windows

Abstract: Electrochromic devices with controllable color switching, low cost, and energy-saving advantages have been widely used as smart windows, rear-view car mirrors, displays, and so on. However, the devices are seriously limited for flexible electronics as they are traditionally fabricated on indium tin oxide (ITO) substrates which will lose their conductivity after bending cycles (the resistance significantly changed from 200 Ω to 6.56 MΩ when the bending radius was 1.2 cm). Herein, we report a new route for large area coassembly of nanowires (NWs), resulting in the formation of multilayer ordered nanowire (NW) networks with tunable conductivity (7-40 Ω/sq) and transmittance (58-86% at 550 nm) for fabrication of flexible transparent electrochromic devices, showing good stability of electrochromic switching behaviors. The electrochromic performance of the devices can be tuned and is strongly dependent on the structures of the Ag and W18O49 NW assemblies. Unlike the ITO-based electronics, the electrochromic films can be bent to a radius of 1.2 cm for more than 1000 bending cycles without obvious failure of both conductivity (ΔR/R ≈ 8.3%) and electrochromic performance (90% retention), indicating the excellent mechanical flexibility. The present method for large area coassembly of NWs can be extended to fabricate various NW-based flexible devices in the future.

Metal halide perovskite nanomaterials: synthesis and applications

Abstract: Nanomaterials refer to those with at least one dimension being at the nanoscale (i.e. <100 nm) such as quantum dots, nanowires, and nanoplatelets. These types of materials normally exhibit optical and electrical properties distinct from their bulk counterparts due to quantum confinement or strong anisotropy. In this perspective, we will focus on a particular material family: metal halide perovskites, which have received tremendous interest recently in photovoltaics and diverse photonic and optoelectronic applications. The different synthesis approaches and growth mechanisms will be discussed along with their novel characteristics and applications. Taking perovskite quantum dots as an example, the quantum confinement effect and high external quantum efficiency are among these novel properties and their excellent performance in applications, such as single photon emitters and LEDs, will be discussed. Understanding the mechanism behind the formation of these nanomaterial forms of perovskite will help researchers to come up with effective strategies to combat the emerging challenges of this family of materials, such as stability under ambient conditions and toxicity, towards next generation applications in photovoltaics and optoelectronics.

Ballistic superconductivity in semiconductor nanowires

Abstract: Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices.

Ultrahigh-Responsivity Photodetectors from Perovskite Nanowire Arrays for Sequentially Tunable Spectral Measurement

Abstract: Compared with polycrystalline films, single-crystalline methylammonium lead halide (MAPbX3, X = halogen) perovskite nanowires (NWs) with well-defined structure possess superior optoelectronic properties for optoelectronic applications. However, most of the prepared perovskite NWs exhibit properties below expectations due to poor crystalline quality and rough surfaces. It also remains a challenge to achieve aligned growth of single-crystalline perovskite NWs for integrated device applications. Here, we report a facile fluid-guided antisolvent vapor-assisted crystallization (FGAVC) method for large-scale fabrication of high-quality single-crystalline MAPb(I1–xBrx)3 (x = 0, 0.1, 0.2, 0.3, 0.4) NW arrays. The resultant perovskite NWs showed smooth surfaces due to slow crystallization process and moisture-isolated growth environment. Significantly, photodetectors made from the NW arrays exhibited outstanding performance in respect of ultrahigh responsivity of 12 500 A W–1, broad linear dynamic rang (LDR) of 15...

Lead-Free Perovskite Nanowire Array Photodetectors with Drastically Improved Stability in Nanoengineering Templates

Abstract: Organometal halide perovskite materials have triggered enormous attention for a wide range of high-performance optoelectronic devices. However, their stability and toxicity are major bottleneck challenges for practical applications. Substituting toxic heavy metal, that is, lead (Pb), with other environmentally benign elements, for example, tin (Sn), could be a potential solution to address the toxicity issue. Nevertheless, even worse stability of Sn-based perovskite material than Pb-based perovskite poses a great challenge for further device fabrication. In this work, for the first time, three-dimensional CH3NH3SnI3 perovskite nanowire arrays were fabricated in nanoengineering templates, which can address nanowire integration and stability issues at the same time. Also, nanowire photodetectors have been fabricated and characterized. Intriguingly, it was discovered that as the nanowires are embedded in mechanically and chemically robust templates, the material decay process has been dramatically slowed dow...

Ag/Au/Polypyrrole Core-shell Nanowire Network for Transparent, Stretchable and Flexible Supercapacitor in Wearable Energy Devices.

Abstract: Transparent and stretchable energy storage devices have attracted significant interest due to their potential to be applied to biocompatible and wearable electronics. Supercapacitors that use the reversible faradaic redox reaction of conducting polymer have a higher specific capacitance as compared with electrical double-layer capacitors. Typically, the conducting polymer electrode is fabricated through direct electropolymerization on the current collector. However, no research have been conducted on metal nanowires as current collectors for the direct electropolymerization, even though the metal nanowire network structure has proven to be superior as a transparent, flexible, and stretchable electrode platform because the conducting polymer's redox potential for polymerization is higher than that of widely studied metal nanowires such as silver and copper. In this study, we demonstrated a highly transparent and stretchable supercapacitor by developing Ag/Au/Polypyrrole core-shell nanowire networks as electrode by coating the surface of Ag NWs with a thin layer of gold, which provide higher redox potential than the electropolymerizable monomer. The Ag/Au/Polypyrrole core-shell nanowire networks demonstrated superior mechanical stability under various mechanical bending and stretching. In addition, proposed supercapacitors showed fine optical transmittance together with fivefold improved areal capacitance compared to pristine Ag/Au core-shell nanowire mesh-based supercapacitors.