CdTe Nanorods Research Articles

Carbon encapsulated CdTe nanorods to execute the enhanced and photo corrosion free hydrogen production

We present carbon-encapsulated CdTe nanorods synthesized through a well-established hydrothermal method. The impact of varying weight percentages of carbon on CdTe nanorods has been explored. XRD, HR-TEM, XPS, Raman and UV-Vis characterization techniques are used to examine the physicochemical and optical properties of prepared compounds. The loading of the carbon layer can be regulated by varying the quantity of sucrose utilized during the synthesis process. The optimized photocatalyst exhibits a superior rate of hydrogen evolution at 247.7 mmol. h−1. g−1cat compared to bare CdTe nanorods. Here, the carbon layer serves a dual purpose as a photocorrosion inhibitor and facilitates electron tunneling for surface reactions. This combined effect of carbon on CdTe is responsible for the observed improvement in the hydrogen evolution rate. As the loading of carbon varies, the activity is aligning closely with the light penetration effect in photocatalysis. Furthermore, we investigated the durability of the optimized photocatalyst, revealing that it retains 89 % of its initial activity even after five cycles. After the activity experiments, essential characterizations such as XRD, Raman and XPS were also analyzed, and the solar to H2 conversion efficiency was computed.

Dynamic synthesis of CdTe NRs: Diameter dependent tuning of PL quenching efficiency for sensitive organic vapor detection

Cadmium telluride (CdTe) is one of the well-explored semiconductors in the history of material science research, because of its innumerable benefits in all dimensional nanostructures. However, no endeavor has been dedicated as of now to understanding the size-dependent tuning of nonradiative emission efficiency and how it influences the sensitive detection of organic vapors (ethanol and acetone) through photoluminescence (PL) quenching mechanism. Herein, the aspect ratio of CdTe nanorods (NRs) is varied by changing its diameter while keeping the axial length constant through electrodeposition into lab made anodic aluminium oxide (AAO) membranes. The growth kinetics and thermodynamics involved while electrodeposition of CdTe NR in each distinct pore diameter of AAO membrane is studied and reasoned. The surface morphology of variable diameter AAO membranes and NRs, respectively fabricated under various electrochemical parameters are observed through a field emission scanning electron microscope. The relation between NRs dimension and structural parameters like d-spacing, crystallite size, band area ratio, and exciton-phonon ratio are extracted from X-ray diffraction and Resonance Raman spectroscopy. The strongly luminescent CdTe NRs, coupled with their chemical durability and organic molecule affinity displayed a sensitive response of ~12 and 6 ppm to ethanol and acetone vapors in the range of 10–100 ppm as a PL sensor. The carrier lifetime measurement through time-correlated single photon counting spectroscopy endorses the role of increased recombination density with a decrease in the diameter of NRs.

I-V Characteristics of Cadmium Telluride Quantum Dots Diode Fabricated by Drop Casting Method

Current (I)-Voltage (V) characterizations of a CdTe quantum dot diode is discussed in this article. The quantum dot diode is fabricated by a simple drop casting method on an n-type Indium Tin Oxide glass substrate. The linear variation of current with respect to applied voltage can be attributed to reduced grain boundary defects and enriched crystallinity. It is also observed that quantum dots can show good current conduction than CdTe nano-rods.

I-V Characteristics of Cadmium Telluride Quantum Dots Diode Fabricated by Drop Casting Method

Current (I)-Voltage (V) characterizations of a CdTe quantum dot diode is discussed in this article. The quantum dot diode is fabricated by a simple drop casting method on an n-type Indium Tin Oxide glass substrate. The linear variation of current with respect to applied voltage can be attributed to reduced grain boundary defects and enriched crystallinity. It is also observed that quantum dots can show good current conduction than CdTe nano-rods.

Controllable preparation of trifold nanorods and nanospheres of cadmium telluride via solvothermal process

In this study, trifold CdTe nanorods and CdTe nanospheres were prepared by the environmentally benign solvothermal process where K2TeO3 and CdCl2 acting as the raw materials, L-ascorbic acid as the reducing agent, ethylene glycol as the solvent and polyvinylpyrrolidone as the surfactant, respectively. The morphology of the products can be regulated by the amount of KOH. Specifically, trifold CdTe nanorods could be prepared with 0.1 g of KOH before the reaction; while CdTe nanospheres were obtained with 0.5 g of KOH. The higher the amount of KOH added, the stronger the reducibility of L-ascorbic acid. For higher reducibility, CdTe crystal nuclei which was continuously generated will first nucleate and grow in the gaps between the rods of the trifold nanorods because of the special morphology and structure of the trifold nanorods. Therefore, with the increasing of the number of CdTe crystal nuclei caused by the accelerated reaction rate, the trifold nanorods will gradually evolve into nanospheres.

Red-to-Blue Photon Upconversion Enabled by One-Dimensional CdTe Nanorods

Photon upconversion via triplet–triplet annihilation creating light in the high-energy regime of the visible spectrum could prove particularly useful in applications such as photocatalysis. Quantum...

Influence of CdS films synthesized by different methods on the photovoltaic performance of CdTe/CdS thin film solar cells**Project supported by Natural Science Foundation of Shandong Province, China (Grant No. ZR2019QF018), National Natural Science Foundation of China (Grant Nos. 61904098 and 11904209), and Natural Science Foundation of Heilongjiang Province of China (Grant No. 2017001).

The cadmium sulphide (CdS) film is grown on cadmium telluride (CdTe) nanorods (NRs) arrays by different methods such as chemical bath deposition (CBD), magnetron sputtering (MS), and homogenous precipitation (HP) techniques. The impact of various deposition methods is explored in detail on the growth of CdTe/CdS composite film, the CdTe/CdS interface property, and solar cell efficiency. Compared to the CBD and HP methods, the MS method can improve the growth of the CdS on CdTe NRs with high crystalline quality. The device based on the CdS film prepared by the MS method demonstrates excellent photovoltaic performance, which has the potential for applications in solar cells.

Facile one-pot solvothermal synthesis of CdTe nanorods and their photoelectrical properties

Uniform CdTe nanorods were synthesized by a PVP-assisted solvothermal process. By assembling CdTe NRs into photodetectors, 2.51 μA of photocurrent and 0.106 A W−1 of responsivity were obtained respectively.

CdTe nanorods for nonenzymatic hydrogen peroxide biosensor and optical limiting applications

Cadmium telluride nanorods (CdTe NRs) have been prepared by the hydrothermal method using ascorbic acid and characterized by x-ray photoelectron spectroscopy, linear and nonlinear optical properties, magnetic properties, and electrochemical analysis. The temperature-dependent magnetic study shows the ferromagnetic behavior. Modified CdTe NRs/glassy carbon electrode was used as the hydrogen peroxide (H2O2) biosensor. It exhibits a linear range (0.67–8.04 μM) with good sensitivity (1326 μA mM−1 cm−2), detection limit (0.1 μM), and a rapid amperometric response time (5 s). It displays a high selectivity toward H2O2 and interference-free phenomenon for other electroactive species such as ascorbic and oxalic acids. The sensor has good selectivity, stability, and reproducibility. CdTe NRs show a better optical limiting property under laser excitation (532 nm, 9 ns) with the two-photon absorption (TPA) coefficient of 12.0 × 10−10 m/W at 100 μJ and an optical limiting of 1.60 J/cm2. These results indicated that the prepared materials could be promising for the detection of hydrogen peroxide and for use as memory storage devices and optical limiters.

Room temperature green luminescence and homogeneous distribution of TGA capped CdTe Nano-Rods

Room temperature green luminescence and homogeneous distribution of Thio Glycolic Acid (TGA) capped CdTe Nano-Rods (NRs) have been reported in this article. Travelling Electron Microscopic (TEM) images show the clear rod shaped morphology for the CdTe Nano-Rods. X-ray Photoelectron Spectroscopic (XPS) analysis supports the successful capping of TGA on CdTe NRs by indicating the presence of sulphur. Photoluminescence (PL) spectra are recorded for these CdTe nano rods and used to assess the quality of the NRs. The observation of excitonic emission at 525.9 nm with full width at half maximum (FWHM) of 25 nm in the PL spectrum recorded at an excitation wavelength of 385 nm clearly signifies the fact that the luminescent samples are mono-dispersed. Further, photoluminescence excitation (PLE) spectrum is recorded at an emission wavelength of 550 nm and the FWHM is found to be 8 nm. From both PL and PLE spectra CdTe Nano-Rods are found to perceive higher homogeneity. From these results it can be evidenced that with narrow FWHM, TGA capped CdTe Nano-Rods being luminescent in the green wavelength region possess higher homogeneity and mono-dispersity.

I-V characteristics and Room Temperature Hall Measurement of CdTe Nano-rods Synthesized by Hydrothermal Method

CdTe Nano-rods have been synthesized using Hydrothermal method. For the confirmation of formation of CdTe in nano metric dimension XRD technique is employed. The diameter of CdTe nano-rods is calculated to be 35.04 nm. SEM image reveals that nano CdTe possess rod shaped morphology. The compositional data is collected with EDAX spectra. Successful capping of thioglycolic acid (TGA) on the surface of CdTe nano-rods is well endorsed by FTIR spectroscpoy technique. Band gap is calculated to be 1.65eV from UV-Visible absorption spectra. I-V characteristics of the CdTe nano-rods showed a linear symmetrical variation at room temperature. This was due to the high crystallinity and homogeneous powder sample of CdTe nano-rods. The higher value of mobility of the order of 1.1264 X 103 cm2/V-s of the as synthesized CdTe nano-rods reveals moderate grain boundaries and less structural defects. Hence compared to bulk CdTe, nano-structured CdTe materials are more ordered in structure and hence improved crystallinity. Room temperature Hall meaasurement employing Van Der Pauw method indicates high resistivity of the order of 107 Ω cm and the as synthesized nano-rods are of p-type material.

High performance supercapacitor behavior of hydrothermally synthesized CdTe nanorods

CdTe nanorods (NRs) have been prepared by hydrothermal process using ascorbic acid as a reducing agent. X-ray diffraction pattern reveals the formation of CdTe with cubic structure. From transmission electron microscopy the morphology of CdTe is found to be NRs with the length and diameter of 176 and 43 nm respectively. Brunauer–Emmett–Telle and Barrett–Joyner–Halenda analyses show the surface area (12.16 m2/g), pore volume (0.13 cm3/g) and pore diameter (44 nm). A high specific capacitance (438 F/g) is obtained at the current density of 2 mA/cm2 by the galvanostatic charge–discharge method. The excellent cyclic stability (95%) and the Coloumbic efficiency (99.7%) have been achieved even after 5000 cycles. The symmetric supercapacitor device exhibits the specific capacitance of 103 F/g at current density of 2.5 mA/cm2 with an energy density of 20.54 Wh/kg. The high density and electrochemical stability of the prepared CdTe electrode is a promising material for electrochemical energy storage devices.

Vertically aligned CdTe nanorods array for novel three-dimensional heterojunction solar cells on Ni substrates

In this study, a uniform CdTe nanorods (NRs) arrays are grown on Ni substrates by a simple one-step electrochemical deposition method. The effects of deposition parameters such as the concentration of reactants and reaction time on the growth of CdTe NRs arrays are systematically investigated. Na2TeO3 and CdSO4 have a significantly different influence on the growth of CdTe NRs. With the increase of Na2TeO3 concentration, the diffraction intensity increases slightly at the peak (111) to promote axial growth. The diffraction intensity of (002) can increase with the concentration of CdSO4 increasing, which is conducive to lateral growth. The morphology of CdTe film varies from a thin layer to nanoparticles, and finally to NRs with the extension of time. Based on the characterization results, the possible growth mechanism of CdTe NRs arrays is proposed. The as-prepared CdTe NRs arrays are then embedded into CdS film, forming a novel three-dimensional (3D) heterojunction photovoltaic device. An extensive study of the effect of NRs length on device performance is presented. The results indicate that the device performance is highly dependent on the length of CdTe NRs, and a power conversion efficiency of 2.50% is obtained for optimal length of 1 μm. The better photovoltaic performance can be attributed to its efficient charge separation and direct pathways for carriers transport. What's more, this novel 3D nanostructured concept suggests great potential for other optoelectronic devices.

Facile Synthesis of CdTe Nanorods from the Growth of Te Nanorods

Facile Synthesis of CdTe Nanorods from the Growth of Te Nanorods

Embedded vertically aligned cadmium telluride nanorod arrays grown by one-step electrodeposition for enhanced energy conversion efficiency in three-dimensional nanostructured solar cells

Vertically aligned CdTe nanorods (NRs) arrays are successfully grown by a simple one-step and template-free electrodeposition method, and then embedded in the CdS window layer to form a novel three-dimensional (3D) heterostructure on flexible substrates. The parameters of electrodeposition such as deposition potential and pH of the solution are varied to analyze their important role in the formation of high quality CdTe NRs arrays. The photovoltaic conversion efficiency of the solar cell based on the 3D heterojunction structure is studied in detail. In comparison with the standard planar heterojunction solar cell, the 3D heterojunction solar cell exhibits better photovoltaic performance, which can be attributed to its enhanced optical absorption ability, increased heterojunction area and improved charge carrier transport. The better photoelectric property of the 3D heterojunction solar cell suggests great application potential in thin film solar cells, and the simple electrodeposition process represents a promising technique for large-scale fabrication of other nanostructured solar energy conversion devices.

Synthesis of uniform cadmium sulphide thin film by the homogeneous precipitation method on cadmium telluride nanorods and its application in three-dimensional heterojunction flexible solar cells

High-density CdTe nanorod arrays are successfully embedded in a uniform and compact CdS layer, forming a novel three-dimensional (3D) CdTe NRs/CdS heterojunction structure. The CdS layer is prepared by homogeneous precipitation (HP) method using decomposition of urea. The effects of temperature and concentration of reactants on the growth and composition of CdS film are investigated in detail. The results demonstrate that the temperature affects the thermal decomposition of urea significantly, and the concentration of CdCl2 and CS (NH2)2 plays an essential role in the compositional ratio of CdS film. Further investigations reveal that, in comparison with the traditional precipitation method, a better coverage of CdS on the surface of CdTe NRs can be obtained by HP method due to the slow and even hydrolysis of urea. Moreover, photovoltaic performance of the novel CdTe NRs/CdS 3D photovoltaic device is also investigated. This study demonstrates that the 3D heterostructure has potential application in thin film solar cells, and the successful deposition of CdS layer on the surface of CdTe NRs by HP method suggests a promising technique for large-scale fabrication of these solar cells.

Two-Dimensional Electronic Spectroscopy Unravels sub-100 fs Electron and Hole Relaxation Dynamics in Cd-Chalcogenide Nanostructures.

We use two-dimensional electronic spectroscopy (2DES) to disentangle the separate electron and hole relaxation pathways and dynamics of CdTe nanorods on a sub-100 fs time scale. By simultaneously exciting and probing the first three excitonic transitions (S1, S2, and S3) and exploiting the unique combination of high temporal and spectral resolution of 2DES, we derive a complete picture for the state-selective carrier relaxation. We find that hot holes relax from the 1Σ3/2 to the 1Σ1/2 state (S2 → S1) with 30 ± 10 fs time constant, and the hot electrons relax from the Σ′ to the Σ state (S3 → S1) with 50 ± 10 fs time constant. This observation would not have been possible with conventional transient absorption spectroscopy due to the spectral congestion of the transitions and the very fast relaxation time scales.

Investigation of the Structural Properties of CdTe and ZnTe Binary Nanorods Under Heat Treatment: Molecular Dynamics Simulations

Investigation of the Structural Properties of CdTe and ZnTe Binary Nanorods Under Heat Treatment: Molecular Dynamics Simulations

Influences of the CdS nanoparticles grown strategies on CdTe nanorods array films: A comparison between successive ionic layer absorption and reaction and chemical bath deposition

The cadmium sulfide (CdS) film is deposited on the surface of cadmium telluride (CdTe) nanorods (NRs) by two different methods, successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) techniques. The influence of the deposition parameters on the properties of the films is investigated. Compared to SILAR, CBD is a simple and time saving technique, which can ensure full coverage and better growth of CdS on the surface of CdTe NRs. The photovoltaic characteristics of CdS sensitized CdTe films are also investigated. It is found that the CdTe/CBD-CdS thin film demonstrates excellent photoelectrical properties, which is ascribed to the large absorption coefficient of the material, indicating the potential applications in solar cells.

Synergistic photovoltaic–thermoelectric effect in a nanostructured CdTe/Bi2Te3 heterojunction for hybrid energy harvesting

A synergistic photovoltaic and thermoelectric effect takes place in a single heterojunction solar cell that consists of a p-type CdTe nanorod array and n-type Bi2Te3 nanostructures.