Optical Properties Of CdS Research Articles

Synthesis and characterization of castor oil and ricinoleic acid capped CdS nanoparticles using single source precursors

ABSTRACT We report the synthesis of castor oil and ricinoleic acid capped CdS nanoparticles by the thermolysis of piperidine (1) and tetrahydroquinoline (2) dithiocarbamate complexes of cadmium(II) at temperatures varying from 190 °C to 300 °C. Reaction parameters such as time and temperature were varied to study their effect on the properties and morphology. The optical properties of CdS were typical of particles that displayed quantum confinement effects. X-ray diffraction studies revealed the existence of both cubic and hexagonal phases depending on the reaction conditions. Ricinoleic acid capped CdS gave cubic phase particles whereas castor oil capped CdS gave both cubic and hexagonal phases dependent on the reaction temperature and the type of complex used. The morphology of the particles varied from oval-short rods to spherical shaped particles with sizes ranging from 10 to 22 nm. Rhodamine B (RhB) dye photodegradation studies of a representative CdS nanoparticles’ sample have been carried out in the presence of halogen light and studied using UV–visible spectroscopy.

Structure and optical properties of CdS:O films by cathode sputtering

AbstractWe have studied the structure and optical properties of CdS:O films deposited on SLG (soda lime glass) substrates by cathode sputtering in the atmosphere of oxygen/argon gases. According to X‐ray diffraction (XRD) and confocal Raman scattering data, the films annealed in vacuum at temperatures above 300 °C exhibited crystalline structure of CdS. On the other hand, XRD, confocal Raman scattering, AFM (atomic force microscopy) and TEM (transmission electron microscopy) data indicated amorphous structure nano‐crystallization in CdS:O films annealed in vacuum at 400 °C. For the films, the emissions located at 3.35 eV were evident from photoluminescence measurements. The origin of this energy gap is discussed by taking into account redistribution of electronic density of states in the amorphous phase and quantum‐size effect. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Synthesis, structures and optical properties of CdS:Cd/Si multi-interface nanoheterojunction

CdS/Si multi-interface nanoheterojunction is synthesized through depositing nanocrystals CdS (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) using a chemical bath deposition method. p-type nanocrystals Si in Si-NPA and n-type nc-CdS construct the multi-interface nanoheterojunction. Due to the reducibility of Si-NPA, a portion of Cd2+ in the interface of Si-NPA and solution are deoxidized and nanocrystals Cd are simultaneously incorporated into the interface of Si–CdS, namely, CdS:Cd/Si-NPA. Through decomposing the resolution XPS spectrum of Cd 3d, the ratio of Cd0 and Cd2+ is about 0.7:1. Three primary color emissions from CdS:Cd/Si-NPA are observed at the room temperature. Optical band gap obtained by the Tauc’s relation and origins of emission bands are studied.

Synthesis, characterization and optical properties of CdS nanowire/SnO2 nanoparticle nano-heterostructures

In this study, CdS nanowire (NW)/SnO2 nanoparticle (NP) nano-heterostructures were successfully synthesized through a facile two-step chemical solution method. The obtained nano-heterostructures were characterized using scanning electron microscopy and transmission electron microscopy, showing that SnO2 nanoparticles with size of about several nanometers grew on the surface of CdS nanowires. Room temperature photoluminescence spectra of the obtained CdS nanowires and CdS NW/SnO2 NP nano-heterostructures were investigated for comparison. The results showed that the near-band-edge emission at 524nm of CdS has a blue shift for CdS NW/SnO2 NP nano-heterostructure, which probably results from the Sn doping in CdS nanowires.

Optical Properties of CdS and CdTe Sensitized ZnO Nanorods

ABSTRACTOptical properties of ZnO-CdTe electrochemically prepared on a core-shell nanostructure (NS) were studied. Numerical simulations based on effective medium approximation give higher absorption than ZnO-CdS samples and a sensitive dependence on CdTe content. The absorption edges for deep black samples found by transmittance (T(λ)) and diffuse reflectance (Rdiff(λ)) measurements were at 1.33eV and 1.55eV, respectively. A split-off band edge was also found by Rdiff(λ) at ∼2.5eV. The red shift observed in T(λ), previously observed in ZnO-CdS, and may confirm the enhancement of sub-bandgap absorption due to the NS nature of samples.

Synthesis, surface morphology, and optical and structural properties of CdS and ZnS nanoparticles

Synthesis of CdS and ZnS nanoparticles in reverse micelles and organic solvents has been carried out. Particles with a hexagonal structure 2–5 nm in size are formed during synthesis. Maintaining the reaction mixture at room temperature leads to the formation of nanoparticles with a cubic structure 100–150 nm in size. The changes in the optical properties of CdS and ZnS nanoparticles, depending on the synthesis method and conditions and on the precursors used, have been investigated. The luminescence characteristics of local surface defects of nanoparticles depend weakly on nanoparticle sizes. The dependence of the fluorescence and phosphorescence intensity of nanoparticle surface defects on the polarity of surrounding solution is demonstrated; thus, these particles can be used as polarity indicators.

SiO<sub>2</sub> Template-assisted Synthesis of CdS Hollow Nanospheres With Enhanced Photocatalytic Properties

CdS hollow nanospheres with enhanced photocatalytic performance have been prepared by employing SiO2 nanospheres as templates with a simple and mild solution reaction at room temperature. Field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) analyses confirmed that these CdS hollow nanospheres possess 370 nm diameter and the wall thickness less than about 30 nm. UV-Vis absorption spectra show that the as-synthesized hollow CdS nanospheres display better light absorption ability than the contracted solid CdS nanospheres. Furthermore, the hollow CdS nanospheres exhibit enhanced activity toward decomposition of target organic pollutant such as Rhodamine B (RhB), under Xe arc lamp irradiation. The calculated rate constants for hollow CdS nanospheres are 5.5 times larger than that of solid CdS nanospheres, which could be ascribed to the improved light absorption ability, adsorption capability due to the hollow structure, and higher charge separation efficiency achieved by shortening the charge transporting path with thinner hollow CdS shell. Keywords: Optical materials, nanofabrications, photocatalysis, optical properties of CdS, clean water and clean energy

Structure and optical properties of CdS:O thin films

AbstractWe have studied structure and optical properties of CdS:O thin films deposited on soda lime glass substrates by rf magnetron sputtering in the atmosphere of oxygen/argon gases. According to X‐ray diffraction and confocal Raman scattering data, the films deposited under oxygen partial pressure below 3% show crystalline structure of CdS. On the other hand, X‐ray diffraction, confocal Raman scattering, TEM (transmission electron microscopy) and XPS (X‐ray photoelectron spectroscopy) data are indicative of amorphization, nano‐crystallization, and inclusion of CdO2 in CdS:O thin films obtained under oxygen partial pressure of 5%. The last films have shown significantly increased transmittance in a spectral range above the energy gap of CdS. The origin of this transmittance is discussed by taking into account redistribution of electronic density‐of‐states in amorphous phase, quantum size effect and contribution of CdO2. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Facile synthesis l-cysteine capped CdS:Eu quantum dots and their Hg2+ sensitive properties

This paper described a facile aqueous route to prepare CdS: Eu quantum dots (QDs) with strong yellow emission using l-cysteine (l-Cys) as the capping ligands. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) confirm that the CdS:Eu QDs have a cubic structure with good crystallinity, the average diameter of the CdS:Eu QDs is about 8nm. The traces of groups adsorbed on CdS:Eu QDs were confirmed via FT-IR spectra. In addition, the synthesis parameters including the concentration of doped Eu3+ ions, the pH value and the reaction time have influence on the optical properties of CdS:Eu QDs. The as-prepared l-Cys capped CdS:Eu QDs were used as a fluorescence probe to detect Hg2+ ions in aqueous media based on fluorescence quenching. The response of l-Cys capped CdS:Eu QDs as a fluorescence probe was linearly proportional to the concentration of Hg2+ ions in the range of 5×10−6 to 1×10−3molL−1 with a limit of detection of 2×10−6molL−1.

Effect of doping Fe and Si on electronic structure and optical Properties of CdS

The geometrical structure, electronic properties and optical properties of CdS and M@CdS (M=Fe, Si) were studied systemically with first principles density functional theory. The band structure and density of states have been calculated to analyze the effect of the doping Fe and Si elements on the electronic properties and magnetic properties of CdS. The results show that all the conductive, magnetic and optical properties of CdS are changed by the doped elements. Both obvious and insignificant changes are found in some cases, which provide helpful guide for preparing doped CdS materials.

Influence of Eu doping on the microstructure and photoluminescence of CdS nanocrystals

The CdS:Eu nanocrystals with a strong white emission have been synthesized by solvothemal method using ethylene glycol as solvents. From X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analysis it was observed that the average diameter of the CdS:Eu nanocrystals is about 5nm. The traces of groups adsorbed on CdS:Eu nanocrystals were confirmed via FT-IR spectra. UV–visible spectroscopy study was carried out to determine the band gap of the nanocrystals and the absorbance peaks showed blue shift with respect to the bulk CdS. From photoluminescence (PL) studies at λex=398nm, the PL emission intensity of CdS:Eu nanocrystals enhanced by doping Eu3+ ions. In addition, the synthesis parameters including the concentration of doped Eu3+ ions, the reaction time, and the reaction temperature have influence on the optical properties of CdS:Eu nanocrystals. The charge compensation agent is a decisive factor for PL emission intensity of CdS:Eu nanocrystals. Furthermore, the storage time and condition on the fluorescence of CdS:Eu nanocrystals were also investigated.

Doped with Ag and Zn effects on electronic structure and optical properties of CdS

The geometry structure, electronic structure and optical properties of zinc bende CdS:M (M = Ag,Zn) were studied systemically using density functional theory based on first-principles ultrasoft pseudopotential method and GGA.The relationship between the distribution of the electronic states and their structures has been analyzed. The dielectric function and the complex refractive index function on doping CdS system have been obtained. The calculation results showed that the hole concentration of Ag-doped CdS is increased, enhanced the conductivity of the material. But the carrier concentration of Al-doped CdS was not changed; the optical band gap were narrowed for Ag-doping, Zn-doping CdS. The mechanism of luminescence has been explained in terms of an analysis of the dielectric function and the complex refractive index function.

Opto-electronic properties of CdS nano particle/carbon nanotube composites

Based on the outstanding optical properties of CdS and excellent electronic properties of single walled carbon nanotube (SWCNT), nano-CdS particle/SWCNT composite materials and nano-CdS/polyethyleneimine (PEI) functionalized SWCNT composite materials are prepared. Their optical and the electrical properties are investigated by using fluorescent light simulated sunlight. The results show that nano-CdS/SWCNT composite material displays a significant negative photo-conductivity phenomenon, while nano-CdS/PEI-SWCNT composite material displays a positive photo-conductivity phenomenon, which can be were explained by using electron-transfer theory. The optical and the electrical properties of two samples are unchanged in the case of large angle bending. Therefore, the nano-CdS/SWCNT composite materials in optical and electrical areas, especially in the emerging field of flexible opto-electronics have a good prospect.

Investigations on structural, vibrational, morphological and optical properties of CdS and CdS/Co films by ultrasonic spray pyrolysis

CdS and CdS/Co films have been deposited on glass substrates by an ultrasonic spray pyrolysis method. The effects of Co incorporation on the structural, optical, morphological, elemental and vibrational properties of these films were investigated. XRD analysis confirmed the hexagonal wurtzite structure of all films and had no impurity phase. While CdS film has (002) as the preferred orientation, CdS/Co films have (110) as the preferred orientation. The direct optical band gap was found to decrease from 2.42 to 2.39eV by Co incorporation. The decrease of the direct energy gaps by increasing Co contents is mainly due to the sp–d exchange interaction between the localized d-electrons of Co2+ ions and band electrons of CdS. After the optical investigations, it was seen that the transmittance of CdS films decreased by Co content. The Raman measurements revealed two peaks corresponding to the 1LO and 2LO modes of hexagonal CdS. The vibrational modes of Cd–S were obtained in the wavenumber range (590–715cm−1) using Fourier transform infrared spectroscopy (FTIR). The elemental analysis of the film was done by energy dispersive X-ray spectrometry.

Structural and Optical Properties of CdS:20%In Films Prepared by Thermal Co-Evaporation method

تم في هذا البحث تحضير أغشية CdS:Inبوساطة التبخير الثنائي في الفراغ بسمك(7500Ao) عند التركيزIn) 20 %) على ارضية زجاجية درجة حرارتها 100c0 وتمت دراسة خصائصها التركيبية والبصرية. أظهرت النتائج ان جميع الاغشية متعددة التبلور وان التشويب بالانديوم أدى الى أرتفاع هذه القمم، كما ان التشويب أدى الى زيادة قيم معامل الامتصاص ومعامل الخمود وثابت العزل الخيالي وتناقص في قيم فجوة الطاقة ونقصان في قيم الانعكاسية ومعامل الانكسار وثابت العزل الكهربائي الحقيقي.

Optical properties of CdS:Mn nanocrystals surface passivated with zinc hydroxide

For the further application performance, CdS:Mn nanocrystals coated with zinc hydroxide (Zn(OH)2) shells were prepared via wet chemical method. Effect of Zn(OH)2 shells on optical properties of CdS:Mn nanocrystals was investigated. X-ray diffraction (XRD) measurements showed that the CdS nanocrystals have hexagonal wurtzite structure. The morphology and components of CdS:Mn/Zn(OH)2 core/shell nanocrystals were successfully measured by transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX). Luminescence properties (intensity and lifetime) of 4T1→6A1 transition of Mn2+ ions in CdS:Mn/Zn(OH)2 core/shell nanocrystals were significantly enhanced as compared with those of unpassivated CdS:Mn nanocrystals. This expected result was caused by the effective, robust passivation of CdS surface states with Zn(OH)2 shells, which consequently suppressed nonradiative recombination transitions.

空位缺陷对CdS电子结构和光学性质的影响

空位缺陷对CdS电子结构和光学性质的影响

Optical properties of CdS and CdS/ZnS quantum dots synthesized by reverse micelle method

The CdS and CdS/ZnS semiconductor quantum dots have been synthesized by reverse micelle method using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) surfactant agent. The quantum dot diameter is about 2.5 to 4 nm depending on the concentration of the surfactant agent. It is interesting that, in contrast to other colloidal methods, the size of quantum dots does not depend on the growth time. The absorption spectra of CdS quantum dots show the narrow size distribution. The photoluminescence (PL) spectra include two bands, the intrinsic emission of CdS nanocrystals and the emission of surface states. There is noticeable increase of the PL intensity and subsequent photostability of CdS/ZnS core-shell quantum dots in comparison with CdS quantum dots without the ZnS shell.

Influence of Mn doping on the microstructure and optical properties of CdS

High quality Cd 1− x Mn x S ( x = 0–0.05) nanorods have been synthesized by a simple chemical route. The nanorods have a uniform single-crystal hexagonal structure and preferentially grow along [0 0 1] direction. The influence of doping Mn 2+ ions on CdS compound semiconductor has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM). Also, investigations about the optical properties of the Mn 2+ doped CdS nanorods were conducted with UV–vis absorption spectroscopy and photoluminescence emission spectroscopy. The luminescence due to Mn 2+ intra-3d transition is clearly observed near 590 nm in Mn-doped CdS nanorods. And the emission intensity is found to enhance with increasing Mn 2+ ion concentration.

Preparation and Optical Properties of CdS: Cu/CdS Nanocrystals

CdS cores were successfully synthesized in noncoordinating solvents.The composite structure of core/shell CdS ∶ Cu/CdS nanocrystals was obtained through the modification of as-prepared Cu2+ ions doped CdS cores using successive ion layer adsorption and reaction(SILAR) technique.The crystal structures,shapes and optical properties of as-synthesized nanocrystals were characterized by X-ray diffraction,transmission electron microscope,UV-Vis Absorption and photoluminescence spectroscope.The results show that the crystal structure of as-prepared CdS ∶ Cu/CdS nanocrystal is zinc blende.Compared with pure CdS nanocrystals,the Cu2+ dopant in CdS leads the surface-state related emission peak shifting to longer wavelength.The surface-state related emission of CdS ∶ Cu nanocrystal can also be adjusted consecutively from 570nm to 620nm by tuning the doping concentration of Cu2+ ions from 2% to 6%.The overcoating of CdS shell can increase the stability of surface-state related emission of CdS ∶ Cu nanocrystals.