scholarly journals APPLICATION OF LUMINESCENCE AND ABSORPTION SPECTRA TO CONTROL THE FORMATION OF A HETEROJUNCTION IN NANOSTRUCTURED RUTILE FILMS SENSITIZED BY CDS QUANTUM DOTS

2019 ◽  
Vol 21 (3) ◽  
pp. 399-405
Author(s):  
Sergei B. Kuschev ◽  
Liana Yu. Leonova ◽  
Anatoly N. Latyshev ◽  
Oleg V. Ovchinnikov ◽  
Elena V. Popova
Keyword(s):  
Quantum Dots ◽  
Absorption Spectra ◽  
Solid Phase ◽  
High Energy ◽  
Cds Nanoparticles ◽  
Energy Structure ◽  
Xenon Lamp ◽  
Cds Quantum Dots ◽  
Cds Nanocrystals ◽  
Thin Fi Lm

The effect of photon processing (FO) on the formation of a heterojunction in the TiO2/QD’sCdS interface obtained by applying separately synthesized CdS quantum dots to the TiO2 film in the rutile phase has been studied. The changes of luminescence spectra and absorption of the investigated samples after this treatment discovered. It is shown that the separation of charge carriers occurs only after irradiation of samples with a powerful light pulse of a xenon lamp.   REFERENCES Kapilashrami M., Zhang Y. , Liu Y.-S., Hagfeldt A., Guo J. Probing the Optical Property and Electronic Structure of TiO2 Nanomaterials for Renewable Ener gy Applications. Chem. Rev., 2014, v. 114, pp. 9662–9707.  https://doi.org/10.1021/cr5000893 Dang T. C., Pham D. L., Le H. C., Pham V. H. TiO2/CdS nanocomposite fi lms: fabrication, characterization, electronic and optical properties. Adv. Nat. Sci. Nanosci. Nanotechnol., 2010, v. 1, p. 015002. https://doi.org/10.1088/2043-6254/1/1/015002 Qian X., Qin D., Bai Y., Li T., Tang X., Wang E., Dong S., Photosensitization of TiO2 nanoparticulate thin fi lm electrodes by CdS nanoparticles. J. Solid State Electrochem., 2001, v. 5, pp. 562–567. https://doi.org/10.1007/s100080000179 Baker D. R., Kamat P. V. Photosensitization of TiO2 nanostructures with CdS quantum dots: Particulateversus tubular support architectures. Adv. Funct. Mater., 2009, v. 19, pp. 805–811. https://doi.org/10.1002/adfm.200801173 Cheng S., Fu W., Yang H., Zhang L., Ma J., Zhao H., Sun M., Yang L. Photoelectrochemical performance of multiple semiconductors (CdS/CdSe/ZnS) cosensitized TiO2 photoelectrodes. J. Phys. Chem. C, 2012, v. 116, pp. 2615–2621. https://doi.org/10.1021/jp209258r Khlyap H. Physics and technology of semiconductor thin fi lm-based active elements and devices. Bentham Science Publisher, 2012. https://doi.org/10.2174/97816080502151090101 Milnes A. G., Feucht D. L. Hetero junctions and metal-semiconductor junctions. Academic Press, 418 p. https://doi.org/10.1016/B978-0-12-498050-1.X5001-6 Ievlev V. M., Latyshev A. N., Kovneristyi Y. K., Turaeva T. L., Vavilova V. V., Ovchinnikov O. V., Selivanov V. N., Serbin O. V. Mechanism of the photonic activation of solid-phase processes. High Energy Chem., 2005, v. 39, pp. 397–402. https://doi.org/10.1007/s10733-005-0078-2 Ievlev V. M., Kushchev S. B., Latyshev A. N., Ovchinnikov O. V., Leonova L. Y, Solntsev K. A., Soldatenko S. A., Smirnov M. S., Sinelnikov A. A., Vozgorkov A. M., Ivikova M. A. Relation of absorption band edge of rutile fi lms and their structure. Inorg. Mater. Appl. Res., 2014, v. 5, pp. 14–21. https://doi.org/10.1134/s2075113314010055 Korolev N. V., Smirnov M. S., Ovchinnikov O. V, Shatskikh T.S. Energy structure and absorption spectra of colloidal CdS nanocrystals in gelatin matrix. Phys. E Low-Dimensional Syst. Nanostructures, 2015, v. 68, pp. 159–163. https://doi.org/10.1016/j.physe.2014.10.042. Ghazzal M. N., Wojcieszak R., Raj G., Gaigneaux E.M. Study of mesoporous cds-quantumdot-sensitized TiO2 fi lms by using x-ray photoelectron spectroscopy and afm. Beilstein J. Nanotechnol, 2014, v. 5, pp. 68–76. https://doi.org/10.3762/bjnano.5.6 Ahire R. R., Sagade A. A., Deshpande N. G., Chavhan S. D., Sharma R., Singh F. Engineering of nanocrystalline cadmium sulfi de thin fi lms by using swift heavy ions. J. Phys. D. Appl. Phys., 2007, v. 40, pp. 4850–4854. https://doi.org/10.1088/0022-3727/40/16/014 Ekimov A., Onushchenko A.A. Size quantization of the electron energy spectrum in a microscopic semiconductor crystal. JETP Lett., 1984, v. 40, pp. 1136–1139. Rolo A. G., Stepikhova M. V., Filonovich S. A., Ricolleau C., Vasilevskiy M. I., Gomes M. J. M. Microstructure and photoluminescence of CdS-doped silica fi lms grown by RF magnetron sputtering. Phys. Status Solidi Basic Res., 2002, v. 232, pp. 44–49. https://doi.org/10.1002/1521-3951(200207)232:1<44::AIDPSSB44> 3.0.CO;2-4 Smyntyna V., Skobeeva V., Malushin N. The nature of emission centers in CdS nanocrystals, Radiat. Meas., 2007, v. 42, pp. 693–696. https://doi.org/10.1016/j.radmeas.2007.01.068 Ehemba A. K., Socé M. M., Domingo J. J., Cisse S., Dieng M. Optimization of the properties of the back surface fi eld of a Cu (In, Ga) Se2 thin fi lm solar cell. American Journal of Energy Research, 2017, v. 5(2), pp. 57–62. https://doi.org/10.12691/ajer-5-2-5  

Immobilized CdS quantum dots in spherical polyelectrolyte brushes: fabrication, characterization and optical properties

2015 ◽  
Vol 3 (15) ◽  
pp. 3745-3751 ◽  
Author(s):  
Yu Cang ◽  
Rui Zhang ◽  
Guixin Shi ◽  
Jianchao Zhang ◽  
Lixiao Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Cds Nanoparticles ◽  
Basic Solution ◽  
Cds Quantum Dots ◽  
Polyelectrolyte Brushes ◽  
Photochemical Stability ◽  
Spherical Polyelectrolyte Brushes

The SPB@CdS nanoparticles exhibit controllable and reversible photoluminescence with pH as a trigger and strong photochemical stability in basic solution.

scholarly journals Optical and Structural Properties of CdS Quantum Dots Synthesized Using (MW-CBD) Technique

2020 ◽  
pp. 44-52
Author(s):  
Ahmed Ahmed S. Abed ◽  
Sattar J. Kasim ◽  
Abbas F. Abbas
Keyword(s):  
Thin Films ◽  
Quantum Dots ◽  
Room Temperature ◽  
Energy Gap ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Optical Energy Gap ◽  
Glass Substrates ◽  
High Adhesion ◽  
Uv Visible

In the present study, the microwave heating method was used to prepare cadmium sulfide quantum dots CdSQDs films. CdS nanoparticles size average obtained as (7nm). The morphology, structure and composition of prepared CdSQDs were examined using (FE-SEM), (XRD) and (EDX). Optical properties of CdSQDs thin films formed and deposited onto glass substrates have been studied at room temperature using UV/ Visible spectrophotometer within the wavelength of (300-800nm), and Photoluminescence (PL) spectrum. The optical energy gap (Eg) which estimated using Tauc relation was equal (2.6eV). Prepared CdS nanoparticles thin films are free from cracks, pinholes and have high adhesion to substrate.

Charge directed assembly of CdTe/CdS nanoparticles inside monocrystalline KH2PO4

CrystEngComm ◽  
2017 ◽  
Vol 19 (45) ◽  
pp. 6804-6810 ◽  
Author(s):  
D. Vorontsov ◽  
S. Filonenko ◽  
A. Kanak ◽  
G. Okrepka ◽  
Y. Khalavka
Keyword(s):  
Quantum Dots ◽  
Potassium Dihydrogen Phosphate ◽  
Directed Assembly ◽  
Cds Nanoparticles ◽  
Dihydrogen Phosphate ◽  
Cds Quantum Dots ◽  
Potassium Dihydrogen

The synthesis of aqueous CdTe/CdS quantum dots (QDs) embedded in potassium dihydrogen phosphate KH2PO4 (KDP) is demonstrated.

scholarly journals Electronic characteristics of CdS quantum dots with defects

2020 ◽  
pp. 28
Author(s):  
I. M. Kupchak ◽  
D. V. Korbutyak ◽  
N. F. Serpak
Keyword(s):  
Quantum Dots ◽  
Optical Absorption ◽  
Valence Band ◽  
Absorption Spectra ◽  
Density Functional ◽  
Optical Absorption Spectra ◽  
Cds Quantum Dots ◽  
Generalized Gradient ◽  
Substitutional Impurity ◽  
Cadmium Vacancy

Using the density functional theory and the generalized gradient approximation, we calculated the atomic structure, the density of electronic states, and the optical absorption spectra of CdS quantum dots containing intrinsic defects — a cadmium vacancy VCd and an interstitial sulfur atom SI, and substitutional impurities — zinc and copper in place of the atom cadmium — ZnCd and CuCd, respectively. The calculations were performed for the Cd33S33 cluster corresponding to the so-called “magic” size of the quantum dot. This size has a minimum of dangling bonds at the surface and allows the using of such a cluster without the passivation. The structural relaxation during the formation of such defects and the distribution of the wave function of the state corresponding to the top of the valence band are analyzed in details. It has been shown that the cadmium vacancy forms local states in the band gap of CdS nanocrystals, and can serve as centers of radiative recombination. Other defects form energy levels in the depths of the valence band or near its top, but whose energy positions do not correspond to the band maxima in the experimental photoluminescence spectra of CdS quantum dots, both undoped and doped with zinc. The calculated optical absorption spectra demonstrate a strong peak in the region of fundamental absorption of CdS for a cluster containing a substitutional impurity of CuCd, in contrast to other systems where no such peaks are observed. In addition, the replacement of the cadmium atom with copper leads to a decrease in the number of chemical bonds to three and, accordingly, to the largest relaxation among the systems studied. This feature is caused by the crystal structure inhomogeneity of copper sulfide CuxS, which, depending on stoichiometry, can be either a semiconductor or a metal.

scholarly journals Synthesis, Characterization and Photophysical Analysis of CDS Nanoparticles

2019 ◽  
Vol 9 (2S2) ◽  
pp. 720-725
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Steady State ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Quenching Process ◽  
Triethyl Amine ◽  
Dimethyl Amine ◽  
Static Nature ◽  
State Luminescence

The CdS quantum dots are prepared in AOT reverse micellar self-assemblies. The quantum dots were prepared from different precursor ratios of 1:1 and 1:2 which yielded different particle size. Steady state luminescence quenching studies were carried out for these quantum dots with N, N-dimethyl amine and triethyl amine. The downward curvature was observed form the SternVolmer plots showing the static nature of the quenching process. The static nature is attributed to presence of the quencher molecules to the quantum dot surface.

BURSTEIN–MOSS SHIFT IN CdS NANOCRYSTALLITES SYNTHESIZED VIA AQUEOUS PRECIPITATION

2012 ◽  
Vol 11 (01) ◽  
pp. 1250003
Author(s):  
PUJA CHAWLA ◽  
S. P. LOCHAB ◽  
NAFA SINGH
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Aqueous Medium ◽  
Absorption Maximum ◽  
Chemical Precipitation ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Excitonic Peak ◽  
Solid Form

We report here the UV-VIS study of CdS nanoparticles synthesized via Chemical precipitation in aqueous medium, the UV-VIS of CdS in aqueous medium shows an excitonic peak at 230 nm, while that of CdS quantum dots in solid form shows an absorption maximum at 480 nm. This bleaching of band gap may be attributed to Moss–Burstein shift in the absorbance edge.

Design of CdS Quantum Dots / Multi-Walled Carbon Nanotubes Hybrid Structures for Photovoltaic Applications

2011 ◽  
Vol 1359 ◽  
Author(s):  
Fayna Mammeri ◽  
Andrea Ballarin ◽  
Marion Giraud ◽  
Lydie Vivet ◽  
Frederic Herbst ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Quantum Dots ◽  
Hybrid Structures ◽  
Cds Nanoparticles ◽  
Diazonium Salts ◽  
Thiol Groups ◽  
Cds Quantum Dots ◽  
Photovoltaic Applications ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

ABSTRACTThis paper presents the preparation of multi-walled carbone nanotubes (CNTs) and CdS nanoparticles based hybrid materials. We aim at comparing two kinds of CNTs’ functionalization by thiol groups in order to demonstrate that the surface chemistry done on the CNTs can direct the morphology of the nanohybrids. Indeed, strong oxidation of CNTs leads to shorter nanotubes opened at their ends, allowing the grafting of mercaptotriethoxysilane whereas the generation of diazonium salts in presence of pristine nanotubes should lead to the functionalization of the whole lateral surface of the nanotubes. CdS nanoparticles can then be anchored to thiol groups, leading to interesting hybrid precursors for photovoltaic applications.

scholarly journals Time and Temperature Dependence of CdS Nanoparticles Grown in a Polystyrene Matrix

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
F. Antolini ◽  
E. Burresi ◽  
L. Stroea ◽  
V. Morandi ◽  
L. Ortolani ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Growth Process ◽  
General Trend ◽  
Cds Nanoparticles ◽  
Size Dependent ◽  
Cds Nanocrystals ◽  
Polystyrene Matrix ◽  
Morphology And Structure ◽  
Cds Qds

Luminescent CdS nanocrystals embedded in a polystyrene matrix were successfully prepared. Thein situgrowth of CdS QDs was realized by thermal treatment of Cd bis(thiolate)/polymer foil at different times and temperatures (240°Cand300°C) of annealing, in order to evaluate their influence on the quantum dots growth process. As a general trend, the increasing of time and temperature of annealing induces a rise of the CdS nanocrystals size into the polymeric matrix. The size distribution, morphology, and structure of the CdS nanoparticles were analysed with HRTEM and XRD experiments. UV-Vis and PL data are strongly size-dependent and were used to investigate the particles' growth process, too. The CdS nanoparticles behavior in solution indicated a general trend of QDs to aggregation. This predisposition was clearly displayed by DLS measurements.

OPTICAL PROPERTIES OF CHEMICALLY PREPARED CdS QUANTUM DOTS IN POLYVINYL ALCOHOL

2009 ◽  
Vol 23 (04) ◽  
pp. 545-555 ◽  
Author(s):  
J. BARMAN ◽  
J. P. BORAH ◽  
K. C. SARMA
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Band Gap ◽  
Blue Shift ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Chemical Route ◽  
Visible Absorption ◽  
Weak Band ◽  
Composite Band

Excitonic effects are observed in the optical absorption and photoluminescence of strongly confined CdS quantum dots embedded in the polymer matrix. CdS nanoparticles of different crystallite sizes have been prepared by chemical route with polymer as a host material. The CdS nanocomposite film was made up of particle smaller than 5 nm and shows a composite band gap up to 3.2 eV, whereas the band gap for bulk hexagonal CdS is about 2.42 eV. Photoluminescence spectra show a strong emission band corresponding to electron–hole recombination and a weak band due to defect emission. The decrease of particle size was monitored from the U-V visible absorption measurement as well as photoluminescence, which suffered blue shift with decrease in particle size. The particle size and surface morphology were also analyzed by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM).

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