CdTe quantum dots precipitation of monodisperse fractions from colloid solutions

Abstract. CdTe nanocrystals were prepared in aqueous solution by the reaction between Cd 2+ and H 2 Te, 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

ON THE ISSUE OF DEFINITION OF THE IMMOVABLE PROPERTY CONCEPT IN FOREIGN LEGISLATIONS

The scientific approaches to the realization of immovable property are considered in the paper. The provisions of foreign legislations, which contain the concept of immovable property, are analysed. The comparison study of these provisions is offered

Electronic properties of surface vacancies in CdS nanocrystals

Structural and electronic characteristics of neutral and charged vacancies of cadmium and sulfur in CdS nanocrystals have been performed using the density functional method with hybrid exchange-correlation functional. Total and partial density of states, formation energies and the energies of thermodynamic transitions were calculated. Based on these theoretical findings and available experimental data, we can confirm the assumption, that the singly charged vacancies of cadmium are the centers of radiative recombination in such the structures. Key words: Cadmium sulfide, nanocrystal,  photoluminescence, vacancy, density functional method.</p

Influence of the dispersion medium on the properties of CdTe micro- and nanocrystals in a colloidal solution

Surface and optical properties of CdTe nanoparticles obtained by grinding (40-150 nm, microcrystals) and colloidal synthesis (1-4 nm, nanocrystals) methods are investigated. It is shown that the most intensive adsorption of stabilizer molecules on the CdTe surface occurs when solvents are better wetting the surface of CdTe particles. It is found that the best stabilization of both the micro- and nanocrystals of CdTe is provided by using methyl and ethyl alcohol as the dispersion medium. The basic characteristics of photoluminescence of CdTe nanocrystals stabilized with thioglycolic acid in deionized water, methanol and ethanol of various concentrations are reported

Photoluminescent Properties of CdTe Nanocrystals in Colloidal Solutions and Polymer Films

Using stabilizers and promoters we have obtained colloidal CdTe nanocrystals (NCs) in aqueous solutions. Incorporation of the CdTe NCs into polymer films has been fulfilled subsequently. It is shown that the use of vinyl acetate-acrylate copolymer as the matrix material for CdTe NC incorporation from colloidal solutions allows to get stable and nontoxic nanoheterogeneous film structures, which are characterized by satisfactory values of the photoluminescence quantum yield. Photoluminescence characteristics of the studied materials have been analyzed. Keywords: cadmium telluride, nanocrystal, vinyl acetate-acrylate copolymer, photoluminescence spectra, photoluminescence quantum yield.</p

Raman mapping of MoS2 at Cu2ZnSnS4/Mo interface in thin film

A Cu2ZnSnS4 (CZTS) thin film deposited on Mo contact film using direct current magnetron sputtering and sulfurized is studied. The morphological and structural investigations are focused on the interface between the CZTS film and the back Mo layer. The film is shown to be polycrystalline with an average grain size of 0.8 µm and of a high conductivity of the grain boundaries. It is also characterized by a suitable elemental composition with a noncritical deviation from the stoichiometry across the film depth. This results in the optical bandgap of 1.48 eV, which is optimal for solar cell absorbers. Raman spectra show low FWHMs of two A-symmetry dominant bands for CZTS thin film, which confirms a high quality of the crystal structure over a large area. At the same time, ZnS secondary phase is found on the film surface, while MoS2 is detected in the depth using a resonant excitation. The Raman mapping shows a non-uniform distribution of MoS2 along the interface between the CZTS film and the back Mo layerThis research was supported in part by National Natural Science Foundation of China [61525503/61620106016/61835009/81727804/61722508/61604098]; the United Program of National Natural Science Foundation of China with Shenzhen [U1613212]; (Key) Project of Department of Education of Guangdong Province [2015KGJHZ002/ 2016KCXTD007]; Guangdong Natural Science Foundation [2014A030312008]; Shenzhen Basic Research Project [JCYJ20170817094728456]; Basic Research Program of the National Academy of Science of Ukraine “Fundamental problems of new nanomaterials and nanotechnology” no. [0115U005037]; and Ministry of Education and Science of Ukraine [0119U100308