Telluride Nanowires Research Articles

Chemically Transformed Ag2 Te Nanowires on Polyvinylidene Fluoride Membrane For Flexible Thermoelectric Applications.

Flexible thermoelectric devices of nanomaterials have shown a great potential for applications in wearable to remotely located electronics with desired shapes and geometries. Continuous powering up the low power flexible electronics is a major challenge. We are reporting a flexible thermoelectric module prepared from silver telluride (Ag2 Te) nanowires (NWs), which are chemically transformed from uniquely synthesized and scalable tellurium (Te) NWs. Conducting Ag2 Te NWs composites have shown an ultralow total thermal conductivity ~0.22 W/mK surpassing the bulk melt-grown Ag2 Te ~1.23 W/mK at ~300 K, which is attributed to the nanostructuring of the material. Flexible thermoelectric device consisting of 4 legs (n-type) of Ag2 Te NWs on polyvinylidene fluoride membrane displays a significant output voltage (Voc ) ~2.3 mV upon human touch and Voc ~18 mV at temperature gradient, ΔT ~50 K, which shows the importance of NWs based flexible thermoelectric devices to power up the low power wearable electronics.

Chemically Transformed Ag2Te Nanowires on Polyvinylidene Fluoride Membrane For Flexible Thermoelectric Applications

AbstractFlexible thermoelectric devices of nanomaterials have shown a great potential for applications in wearable to remotely located electronics with desired shapes and geometries. Continuous powering up the low power flexible electronics is a major challenge. We are reporting a flexible thermoelectric module prepared from silver telluride (Ag2Te) nanowires (NWs), which are chemically transformed from uniquely synthesized and scalable tellurium (Te) NWs. Conducting Ag2Te NWs composites have shown an ultralow total thermal conductivity ~0.22 W/mK surpassing the bulk melt‐grown Ag2Te ~1.23 W/mK at ~300 K, which is attributed to the nanostructuring of the material. Flexible thermoelectric device consisting of 4 legs (n‐type) of Ag2Te NWs on polyvinylidene fluoride membrane displays a significant output voltage (Voc) ~2.3 mV upon human touch and Voc ~18 mV at temperature gradient, ΔT ~50 K, which shows the importance of NWs based flexible thermoelectric devices to power up the low power wearable electronics.

Growth and characterization of germanium telluride nanowires via vapor–liquid–solid mechanism

Phase-change materials (PCMs), which can transition reversibly between crystalline and amorphous phases, have shown great promise for next-generation memory devices due to their nonvolatility, rapid switching periods, and random-access capability. Several groups have investigated phase-change nanowires for memory applications in recent years. The ability to regulate the scale of nanostructures remains one of the most significant obstacles in nanoscience. Herein, we describe the growth and characterization of germanium telluride (GeTe) nanowires, which are essential for phase-change memory devices. GeTe nanowires were produced by combining thermal evaporation and vapor–liquid–solid (VLS) techniques, using 8 nm Au nanoparticles as the metal catalyst. The influence of various growth parameters, including inert gas flow rate, working pressure, growth temperature, growth duration, and growth substrate, was examined. Ar gas flow rate of 30 sccm and working pressure of 75 Torr produced the narrowest GeTe nanowires horizontally grown on a Si substrate. Using scanning electron microscopy, the dimensions, and morphology of GeTe nanowires were analyzed. Transmission electron microscopy and energy-dispersive x-ray spectroscopy were utilized to conduct structural and chemical analyses. Using a SiO2/Si substrate produced GeTe nanowires that were thicker and lengthier. The current–voltage characteristics of GeTe nanowires were investigated, confirming the amorphous nature of GeTe nanowires using conductive atomic force microscopy. In addition, the effects of the VLS mechanism and the Gibbs–Thomson effect were analyzed, which enables the optimization of nanowires for numerous applications, such as memory and reservoir computing.

Rationally Designed ZnTe@C Nanowires with Superior Zinc Storage Performance for Aqueous Zn Batteries.

Te-based materials with excellent electrical conductivity and ultra-high volume specific capacity have attracted much attention for the cost-efficient aqueous Zn batteries. However, the construction of functional structures with mild volume expansion and suppressed shuttle effects, enabling an expanded lifespan, is still a challenge for conversion-type materials. Herein, the carbon-coated zinc telluride nanowires (ZnTe@C NWs) are rationally designed as a high-performance cathode material for aqueous Zn batteries. The carbon-coated1Dnanostructure could not only provide optimized transmission path for electrons and ions, but also help to maintain structure integrity upon volume variation and suppress intermediates dissolution, endowing the ZnTe@C NWs with improved cycling stability and reaction kinetics. Consequently, a reversible six-electron reaction mechanism of ZnTe@C NWs based on Te2- /Te4+ conversion with excellent output capacity (586 mAh g-1 at 0.1 A g-1 ) and lifespan (>250 mAh g-1 retained for 400 cycles at 1 A g-1 ) is eventually achieved.

Flexible Thermoelectric Films Based on Bi2Te3 Nanowires and Boron Nitride Nanotube Networks with Carbon Doping.

Energy recovery and reuse, industrial waste heat, and thermal energy recovery and conversion in emerging electronic devices are topics of widespread interest. Flexible composite thermoelectric (TE) films have become the key to TE conversion, and many studies and synthesis methods related to them have made great progress. However, little research has been performed on the corresponding composites of typical TE materials with low-dimensional nanotubular materials, particularly modulation of the overall TE properties using doped low-dimensional nanotubular materials. In this work, high-quality bismuth telluride (Bi2Te3) nanowires and boron nitride nanotubes (BNNTs) were prepared using electrolytic deposition and high-temperature catalytic deposition, respectively. Bi2Te3-BNNTs composite films were prepared using a solvent hot pressing method. The Bi2Te3-BNNTs composite film conductivity reached 179.6 S/cm at room temperature (300 K), the corresponding Seebeck coefficient was 171.4 μV/K, and the power factor (PF) was 52.8 nW/mK2. Carbon doping of BNNTs resulted in carbon-boron nitride nanotubes (BCNNTs), and Bi2Te3-BNNTs composite films were prepared. The Bi2Te3-BCNNTs composite films obtained a conductivity of 4629.6 S/cm, at room temperature (300 K), a corresponding Seebeck coefficient of 181.2 μV/K, and a PF of 1520.0 nW/mK2. This study has important reference value for the application of TE conversion. Moreover, the electrical conductivity decreased by no more than 10% after 400 cycles of bending tests, and the electrical conductivity showed signs of recovery after repressing thermally, which undoubtedly proves that Bi2Te3-BCNNTs composite films have good flexibility and thermal stability, and this has contributed to the application and promotion of flexible thermoelectric materials.

Triboelectric Nanosensor Integrated with Robotic Platform for Self-Powered Detection of Chemical Analytes

Rapid on-site detection of hazardous chemicals is imperative for remote security and environmental monitoring applications. However, the implementation of current sensing technologies in real environments is limited due to an external high-power requirement, poor selectivity and sensitivity. Recent progress in triboelectric nanosensors and nanogenerators presents tremendous opportunities to address these issues. Here, we report an innovative self-powered triboelectric nanosensor for detection of Hg2+ ions, a harmful chemical pollutant, in a rapid single step on-site detection mechanism. Based on the mechanism of solid-liquid contact electrification, tellurium nanowire (Te NW) arrays serving as a solid triboelectric material as well as the sensing probe underwent periodic contact and separation with the Hg2+ solution, leading to the in situ formation of mercury telluride nanowire (HgTe NWs) owing to the selective binding affinity of Te NWs toward Hg2+ ions. To realize the on-site sensing potential, Te NW arrays were mounted onto the robotic hands equipped with additional wireless transmission functionality for rapid detection of Hg2+ ions in resource-limited settings by employing a simple "touch and sense" mechanism. Such a demonstration of direct integration of self-powered sensors with robotics would lead to the development of low-cost, automated chemical sensing machinery for the on-field detection of harmful analytes.

The synthesis of bismuth telluride nanowires with a high aspect ratio via precise regulation of growth rates

It is challenging to obtain one-dimensional nanowires with a high aspect ratio. Herein, we developed a controllable hydrothermal method to synthesize single-crystalline bismuth telluride (Bi2Te3) nanowires with a high aspect ratio. The effects of growth conditions including template, temperature, surfactant polyvinyl pyrrolidone (PVP) dosage, and pH value on the aspect ratio of Bi2Te3 nanowires were studied. The results show that Te nanowire templates not only support the epitaxial growth but also supply the Te source of Bi2Te3 nanowires. The reaction temperature, surfactant PVP, and pH were carried out to adjust the nucleation and diffusion rates of Bi and Te, thus controlling the growth rates of Bi2Te3 nanowires. The obtained Bi2Te3 nanowires have an aspect ratio of up to 100 (length of 7 µm and width of 70 nm).

Lead Telluride Nanowires for Surface Passivation in Cadmium Telluride Photovoltaics

Cadmium telluride (CdTe) is one of the leading technologies in thin-film solar cells; however, its open-circuit voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> ) is limited by defects associated with polycrystalline nature, carrier concentration, and interfaces. To overcome the deep work function of the CdTe absorber and create a passivating back contact interface, a lattice-matched and highly doped p-type material is needed to function as a buffer layer between the CdTe and a highly conductive electrode. Here, we report that lead telluride (PbTe) nanowires (NWs) serve to passivate the CdTe back contact, enhancing the optoelectronic properties and device performance. The steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements showed improved PL intensity and minority carrier lifetime for devices utilizing a PbTe NW back buffer, consistent with surface passivation. Additionally, the devices employing PbTe NWs showed improved V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> and fill factor (FF). For instance, implementation of PbTe NWs as a passivating layer to CdS/CdTe solar cells yielded a photoconversion efficiency of 14.8% (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> = 855 mV and FF = 77.3%), whereas the control device reached 14.0% (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> = 840 mV and FF = 75.9%). This improvement in V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> and FF is consistent with the reduction in both back-barrier height and recombination losses observed for devices with the PbTe NW back buffer.

Spin and Orbital Spectroscopy in the Absence of Coulomb Blockade in Lead Telluride Nanowire Quantum Dots

We investigate quantum dots in semiconductor PbTe nanowire devices. Due to the accessibility of ambipolar transport in PbTe, quantum dots can be occupied both with electrons and holes. Owing to a very large dielectric constant in PbTe of order 1000, we do not observe Coulomb blockade which typically obfuscates the orbital and spin spectra. We extract large and highly anisotropic effective Landé g-factors, in the range 20-44. The absence of Coulomb blockade allows direct readout, at zero source-drain bias, of spin-orbit hybridization energies of up to 600 \muμeV. These spin properties make PbTe nanowires, the recently synthesized members of group IV-VI materials family, attractive as a materials platform for quantum technology, such as spin and topological qubits.

Electrochemical epitaxial PbTe nanowires photodetector for NIR response

Lead telluride nanowires deposited by electrochemical atomic layers have broad application prospects in the field of photodetectors. In this work, using the method of electrochemical atomic layer deposition, we obtained different morphologies of lead telluride materials by controlling the deposition parameters, such as deposition time, temperature, and potential, and characterized them using SEM, TEM, XPS, and other techniques. A lead telluride nanowire detector with good performance was prepared. The photoresponsivity of the detector is 102 mA W−1, the detectivity is 2.1 × 108 Jones, and the response time and recovery time are 0.52 s and 0.54 s respectively at 2.7 μm wavelength laser irradiation.

Screen-printed bismuth telluride nanostructured composites for flexible thermoelectric applications

We herein report the results of a facile two-step surfactant assisted reflux synthesis of bismuth telluride (Bi2Te3) nanowires (NWs). The as-synthesised NWs had diameters ranging from 70 to 110 nm with a length varying between 0.4 and 3 µm and a preferential lattice orientation of (0 1 5) as determined by grazing incidence x-ray diffraction. We demonstrate for the first time that a solvent/binder paste formulation of N-methyl-2-pyrrolidone/polyvinylidene fluoride (PVDF) is suitable for screen-printing the Bi2Te3 NWs with the potential for the fabrication of flexible thermoelectric (TE) materials. The wt% of PVDF in the composite films was varied from 10% to 20% to identify the optimal composition with a view to achieving maximum film flexibility whilst retaining the best TE performance. The films were screen-printed onto Kapton substrates and subjected to a post-printing annealing process to improve TE performance. The annealed and screen printed Bi2Te3/PVDF NW composites yielded a maximum Seebeck coefficient −192 µV K−1 with a power factor of 34 µW m−1K−2 at 225 K. The flexible screen printed composite films were flexible and found to be intact even after 2000 bending cycles.

Production of Size-Controlled Gold Nanoclusters for Vapor-Liquid-Solid Method.

This study demonstrated the deposition of size-controlled gold (Au) nanoclusters via direct-current magnetron sputtering and inert gas condensation techniques. The impact of different source parameters, namely, sputtering discharge power, inert gas flow rate, and aggregation length on Au nanoclusters’ size and yield was investigated. Au nanoclusters’ size and size uniformity were confirmed via transmission electron microscopy. In general, Au nanoclusters’ average diameter increased by increasing all source parameters, producing monodispersed nanoclusters of an average size range of 1.7 ± 0.1 nm to 9.1 ± 0.1 nm. Among all source parameters, inert gas flow rate exhibited a strong impact on nanoclusters’ average size, while sputtering discharge power showed great influence on Au nanoclusters’ yield. Results suggest that Au nanoclusters nucleate via a three-body collision mechanism and grow through a two-body collision mechanism, wherein the nanocluster embryos grow in size due to atomic condensation. Ultimately, the usefulness of the produced Au nanoclusters as catalysts for a vapor–liquid–solid technique was put to test to synthesize the phase change material germanium telluride nanowires.

Contact resistance optimization for development of thermoelectric modules based on bismuth telluride nanowires

This paper presents a study of the contact resistance between a metal M (M = Ni, Pt, and Au) and an array of n-type Bi2Te3−xSex thermoelectric nanowires deposited through the electrodeposition process in the alumina membrane. Contact resistances between different metals and thermoelectric nanowires have been tested and characterized after optimization of the mechanical thinning and polishing process of the top part of the membrane. A low areal contact resistance of 87 µΩ cm2 obtained with Au as the contact electrode is very encouraging for the development of thermoelectric modules based on nanowires in their membranes.

Cooling property and application of Au–Bi2Te3 heterojunction nanowire array based on AAO template

In this work, selective radiation material was used to change heat transport of hot side, a novel heterostructure cooler, constructed by gold (Au)—bismuth telluride (Bi2Te3) nanowires array was reported experimentally. The heterostructure was fabricated by electrochemical deposition based on porous anodic alumina template (AAO). The Au nanowire cluster array is used as an infrared selective radiation surface to optimize heat transport of the heat side. And the Bi2Te3 nanowires generate thermoelectromotive force between the two sides of the device due to thermoelectric effect. More interestingly, the Au nanowire ends produce an interface between the metal and semiconductor to enhance the temperature difference, as the interfacial phonon scattering suppresses thermal conductivity. The co-effects create a linear-like relationship between the temperature difference and the applied heating strength to make the heating source hide from infrared detection. At a heating temperature of 170 °C, the radiation temperature difference arrives 16 °C in the Au–Bi2Te3 heterojunction, (increased by 200% to that in Bi2Te3 single phase), given by an intriguing demonstration of infrared camouflage effect. The Au–Bi2Te3 nanowires heterojunction device can not only realize infrared camouflage, but also convert the heat into electrical energy, which provides a new idea for the development of materials.

Copper telluride nanowires for high performance electrocatalytic water oxidation in alkaline media

Active, cost-effective and durable electrocatalysts composed of earth abundant elements for water oxidation reaction are significantly important in the research domain of sustainable energy production and storage. Here, we present hydrothermally synthesized copper telluride nanowires (Cu7Te4-NW) for high activity water oxidation. The successful synthesis of nanoscale catalytic material is characterized through various techniques. The electrocatalyst exhibits the higher intrinsic catalytic performance at very low overpotentials (277 mV), smaller Tafel slope (33 mV dec−1), least charge transfer resistance (1.5 Ω), higher turnover frequency value (2.57 s−1 @ 350 mV), and long-term durability (100 mA for 24 h @ 1.66 V vs RHE), surpassing the electrocatalytic efficiency for Oxides of noble metals i.e. Ru and Ir. DFT calculations demonstrate that the energy for hydroxyl attachment is highly favourable onto the porous substrate of Cu7Te4-NW, further approving its remarkable properties for heightened electrocatalytic water oxidation performance. The highly atypical OER catalytic performance is discovered for Cu7Te4-CF that can be succinctly attributed to its extraordinary structural attributes yielding greater surface area and highly exposed catalytic active sites. The novel catalyst of Cu7Te4-CF can be benchmarked as an alternative for previously scrutinized metal chalcogenides based electrocatalysts for OER due to its efficacious catalytic performance.

Excited state dynamics in a sodium and iodine co-doped lead telluride nanowire

ABSTRACT Materials that convert wasted heat into electricity are needed to help solve global warming and other climate challenges. Thermoelectric nanowires are novel metamaterials for such applications. Non-adiabatic coupling computations are critical in understanding thermally activated charge transfer in thermoelectric materials. Here, non-adiabatic computations are used to evaluate electron relaxation rates in lead telluride nanowires. This work reports results on PbTe (lead telluride) atomistic models doped with sodium and iodine that contain 288 atoms in simulation cells with periodic boundary conditions. The calculations are performed on the basis of ground-state DFT under the VASP software. The transitions between states are modelled in terms of Redfield equation of motion parameterised by on-the-fly non-adiabatic couplings along thermalised molecular dynamic trajectory. The initial states are approximated by the promotion of an electron from occupied to unoccupied Kohn–Sham orbital. In each transition, the change of the energy and spatial charge distribution with respect to time were calculated, demonstrating formation of charge transfer. The trends of electron and hole relaxation rates comply with the energy gap law.

Necklace-like ultrathin silver telluride nanowire films and their reversible structural phase transition

Ultrathin necklace-like Ag2Te nanowires with a diameter of 10 nm and a length of several micrometers are fabricated by a simple solution-based process at low temperature, and the Ag2Te nanowire films are fabricated by a Langmuir-Blodgett technique. A reversible structural phase transition of the nanowire films obtained can be observed, and in addition is also reflected by the electrical properties.

Thermoelectric Power of Silver Telluride Thin Films and its Thermal Conductivity Applications

The hydrothermal technique was used to create straight single crystal silver telluride nanowires with a diameter of around 200 nm and a length of up to micrometers of decades. There has been no template or surfactant used in the process. As-synthesized products are high purity and well-crystallized, confirmed by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectrum, transmission electron microscopy (TEM), and a high-resolution SAED pattern. Differential scanning calorimetry was used to observe the reversible structural phase shift from the low-temperature monoclinic structure to the high-temperature face-centered cubic structure. Furthermore, the dramatic drop in electrical current in a single nanowire at the phase transition temperature is revealed, paving the way for future research into the manufacturing of one-dimensional nanoscale devices. Silver telluride (Ag2Te) has large thermoelectric coefficients and it was tested by using resistor graph and calculated the values of it, thermal conductivity and Seebeck coefficient were discussed with respect to the temperature of thin films. Semiconductors were superior thermoelectric material due to higher ratio of electrical and thermal conductivities. Therefore, the AgTe thin films deposited on indium tin oxide (ITO) substrates were employed, thermoelectric power and thermal conductivity measurements, respectively.

Fabrication and Electrical Properties of Silver Telluride Nanowires.

As a new topological insulator material, the β-phase silver telluride (Ag₂Te) nanowire is a narrow bandgap semiconductor, which is attractive for its excellent properties. In this study, Ag₂Te nanowires were synthesized by one-step hydrothermalmethod. The nanowires showed good electrical properties with maximum drain-source voltage of 1.5 V, and the output current was up to 20 μA. The gate voltage has a significant effect on output current for the device. The Ag₂Te nanowires will have more extensive and in-depth applications in the fields of optoelectronics and thermoelectricity.

Insights into the mechanical properties and fracture mechanism of Cadmium Telluride nanowire

Semiconducting nanowires (NWs), key building blocks in nanotechnology with many potential applications, are stirring the attention of the scientific world because of their many unique properties. Cadmium telluride (CdTe) single crystal nanowires, with Zinc Blende (ZB) crystal configuration, have become the focus of interest nowadays due to its promising application in Opto-electro-mechanical nanodevices. However, due to the lack of complete insight into their mechanical deformation, it is necessary to thoroughly study the CdTe nanowires. In this study, molecular dynamics simulations have been used to investigate the mechanical behavior of CdTe nanowires (NWs) by varying size, temperature, crystal orientation, and strain rate under tension and compression. Results show that the fracture strength of the [111]-oriented CdTe NWs is always higher than that of the [110]-oriented CdTe NWs under tension whereas, in compression, the fracture strength of the [111]-oriented CdTe NWs is significantly lower than that of the [110]-oriented CdTe NWs. Moreover, upon applying the tensile load along NWs growth direction, the [111]-oriented CdTe NWs fail by creating void in [10-1] direction due to bond breaking in [1-21] direction regardless of temperature and NW size. Under compression, the [111]-oriented nanowires show buckling and plasticity. It has also been observed that size has a negligible effect on the tensile behavior but in compression, the behavior is size-dependent. Both tensile and compressive strengths show an inverse relation with temperature. Finally, the impact of strain rate on [111]-oriented CdTe NWs are also studied where higher fracture strengths and strains at higher strain rates have been found under both tension and compression. With increasing the strain rate, the number of voids is also increased in the NWs. This study will help to design CdTe NWs based devices efficiently by presenting an in-depth understanding of the failure behavior of the [111]-oriented CdTe NWs.