Piezoelectric Response of Cadmium Sulfide Nanorod Crystals Grown from Gas Phase by Using Ag and Au Catalyst

The paper describes macroscopic and AFM measurements of piezoelectric response of a macroscopic array of nanorod crystals of CdS and single nanorod crystal of CdS, respectively. The CdS nanorod crystals grown using Ag catalyst are presented for the first time. It is shown that these crystals have an irregular shape of six-sided polyhedron and demonstrate piezoelectric response similar to their counterpart crystals grown from Au catalyst which have a perfect hexagonal shape and wurtzite structure. The irregular shape of Ag catalyzed CdS nanocrystals is discussed based on the assumption of their sphalerite crystal symmetry

CdTe quantum dots precipitation of monodisperse fractions from colloid solutions

CdTe nanocrystals were prepared in aqueous solution by the reaction between Cd²⁺ and H₂Te, obtained electrochemically in a galvanostatic cell, in the presence of thioglycolic acid. Subsequently, we have investigated precipitation of monodisperse fractions of CdTe quantum dots from polydisperse colloid solutions. In addition, the photoluminescence characteristics of these systems were studied in detail

Injection Spectroscopy of Deep Traps in Nanostructured Films of Cadmium Sulfide

Nanocrystallin CdS films with controlled stoichiometry deposited by CSVS were investigated by meth-od of the current-voltage characteristics in ITO/CdS /In structures. It was shown that in the case of cadmi-um excess (S Cd) charge flow mechanism is deter-mined by monomolecular recombination. In the band gap of CdS with excess of cadmium there was detect-ed localized states with energy Et = 0.514 ± 0.026 eV, while in the material with Excess sulfur there are two localized states with energy Et1 = 0.514 ± 0.026 eV and Et2 = 0.700 ± 0.026 eV. Full concentration of lo-calized states is more than 2·1021 m-3 – 5·1022 m-3. Dependence of injection in parameters and nature of in-jection in the structures based on nanostructured CdS films on their stoichiometry was determined When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3524

Injection Spectroscopy of Deep Traps in Nanostructured Films of Cadmium Sulfide

Nanocrystallin CdS films with controlled stoichiometry deposited by CSVS were investigated by meth- od of the current-voltage characteristics in ITO/CdS /In structures. It was shown that in the case of cadmi- um excess (S <Cd) charge flow mechanism both in the dark and under illumination is determined by bimo- lecular recombination in the material. In the case of excess sulfur (S>Cd) charge flow mechanism is deter- mined by monomolecular recombination. In the band gap of CdS with excess of cadmium there was detected localized states with energy Et = 0.514 ± 0.026 eV, while in the material with Excess sulfur there are two localized states with energy Et1 = 0.514 ± 0.026 eV and Et2 = 0.700 ± 0.026 eV. Full concentration of localized states is more than 2·1021 m-3 – 5·1022 m-3. Dependence of injection in parameters and nature of injection in the structures based on nanostructured CdS films on their stoichiometry was determined. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3390

Macroscopic versus microscopic photovoltaic response of heterojunctions based on mechanochemically prepared nanopowders of kesterite and n-type semiconductors

Mechanochemically prepared nanopowder of selenium-free kesterite Cu2ZnSnS4 (CZTS) in combination with n-type semiconductors, i.e., CdS, ZnO and TiO2, was tested in planar and bulk-heterojunction solar cells. The samples have been studied by macroscopic current-voltage (I-V) measurements and Kelvin-probe atomic-force microscopy (KPFM). KPFM images taken under light illumination showed the distribution of the potential across the surface, with negative potential on the n-type semiconductor domains and positive potential on the CZTS domains, which indicated charge separation at the interface of the counterparts. The best result was found for the CdS-CZTS composition, which showed a potential difference between the domains up to 250 mV. These results were compared with the planar heterojunctions of CdS/CZTS and TiO2/CZTS, where CZTS nanopowder was pressed/deposited directly onto the surface of films of the corresponding n-type semiconductors. Again, I-V characteristics showed that cells based on CdS/CZTS heterojunctions have the best performance, with a photovoltage up to 200 mV and photocurrent densities up to 0.1 mA/cm2. However, the carrier generation was found to occur mainly in the CdS semiconductor, while CZTS showed no photo-response and served as the hole-transporting layer only. It is concluded that sensitization of the kesterite powder obtained by mechanochemical method is necessary to improve the performance of the corresponding solar cells