A5055539416- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Advanced Thermoelectric Materials and Devices
- Crystal Structures and Properties
- Phase-change materials and chalcogenides
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Arctic and Russian Policy Studies
- Ga2O3 and related materials
- Advanced DC-DC Converters
- Semiconductor materials and interfaces
- Graphene and Nanomaterials Applications
- Nanocluster Synthesis and Applications
- Environmental Sustainability and Technology
- Perovskite Materials and Applications
- Marine and environmental studies
- Solar Thermal and Photovoltaic Systems
- Advanced Photocatalysis Techniques
V.E. Lashkaryov Institute of Semiconductor Physics
2017-2024
Chemnitz University of Technology
2021-2024
National Academy of Sciences of Ukraine
2016-2023
Joint Research Center
2022
Kyiv City Clinical Oncology Center
2016-2018
A Raman spectroscopic study of Cu2ZnSnS4 (CZTS) nanocrystals (NCs) produced by a "green" synthesis in aqueous solutions is reported. Size-selected CZTS NCs reveal phonon confinement that manifests itself an upward shift the main peak about 3-4 cm-1 varying NC diameter from 3 to 2 nm. non-monotonous and narrowing are attributed special shape dispersion this material. Moreover, method sample preparation, nature supporting substrate photoexcitation regime found crucially influence spectra...
The aim of this study is to establish reliable spectroscopic fingerprints compounds that may form as secondary phases in Cu2ZnSnS4 (CZTS) nanocrystals (NCs) synthesized by “green” colloidal chemistry directly aqueous solutions or during post-processing NC films for photovoltaic applications. For purpose, we investigated a series binary and ternary compound NCs under the same conditions quaternary CZTS NCs. capabilities combined Raman X-ray photoemission (XPS) spectroscopy are used identify...
ZnO nanocrystals doped with Nd, Gd, and Er were synthesized using a soft chemical process in ambient atmosphere. Pseudospherical hexagonal (NC) of the wurtzite phase mean size (7.4 ± 1.7) nm obtained. The presence rare earth (RE) dopants was confirmed by X-ray fluorescence (XRF) spectroscopy. exhibited simultaneously narrow excitonic- broad trap/surface-related photoluminescence (PL), both which affected doping RE atoms. Doping reduced total PL intensity, suppressing excitonic emission...
The transformation of the vibrational spectrum Cu<sub>2</sub>Zn(Sn<sub>1−x</sub>Ge<sub>x</sub>)S<sub>4</sub>single crystals over entire composition range (0 ≤<italic>x</italic>≤ 1) is studied experimentally as well theoretically.
Ag–Ga–S quantum dots (QDs) are obtained by colloidal synthesis in aqueous solutions with glutathione ligands at mild conditions. The QDs can be assigned to metastable orthorhombic, rhombohedral, or rocksalt‐type phases, assuming a significant internal pressure within crystallites, while the conventional tetragonal AgGaS 2 phase is less likely formed. Similarly these reveal relatively narrow indirect bandgap contrary wide and direct of . Size‐selected fractions separated repeated centrifuging...
The effect of flash-lamp annealing (FLA) on the re-crystallization thin films made colloidal Cu2ZnSnS4 nanocrystals (NCs) is investigated by Raman spectroscopy. Unlike similar previous studies NCs synthesized at high temperatures in organic solvents, this work, which have diameters as small 2-6 nm, were under environmentally friendly conditions aqueous solution using molecules stabilizers. We establish range FLA providing an efficient film NCs, while preserving their kesterite structure and...
The synthesis of (Cu,Ag)-Zn-Sn-S (CAZTS) and Ag-Zn-Sn-S (AZTS) nanocrystals (NCs) by means “green” chemistry in aqueous solution their detailed characterization Raman spectroscopy several complementary techniques are reported. Through a systematic variation the nominal composition quantification constituent elements CAZTS AZTS NCs X-ray photoemission (XPS), we identified vibrational IR fingerprints both main phase secondary phases Ag-Zn-S Ag-Sn-S compounds. formation Ag-S cannot be avoided...
Cu-Zn-Sn-Te (CZTTe) is an inexpensive quaternary semiconductor that has not been investigated so far, unlike its intensively studied CZTS and CZTSe counterparts, although it may potentially have desirable properties for solar energy conversion, thermoelectric, other applications. Here, we report on the synthesis of CZTTe nanocrystals (NCs) via original low-cost, low-temperature colloidal in water, using a small-molecule stabilizer, thioglycolic acid. The absorption edge at about 0.8–0.9 eV...
Cu2ZnSnS4 (CZTS) is an intensively studied potential solar cell absorber and a promising thermoelectric (TE) material. In the form of colloidal nanocrystals (NCs), it very convenient to thin films on various substrates. Here, we investigate composites CZTS NCs with PEDOT:PSS, widely used photovoltaics polymer. We focus investigation structural stability both polymers in composite different NC-to-polymer ratios. pristine those subjected flash lamp annealing (FLA) or laser irradiation power...
AgGaGeS4 is an emerging material with promising nonlinear properties in the near- and mid-infrared spectral ranges. Here, experimental phonon spectra of single crystals synthesized by a modified Bridgman method are presented. The infrared absorption reported. They obtained from fitting reflectivity to model dielectric function comprising series harmonic oscillators. In Raman spectra, several modes registered, which were not detected previous works. analysis vibrational bands performed on...
Thin films of colloidal CZTS nanocrystals (NCs) synthesized using a “green” approach in water with variation the copper-to-tin ratio are investigated by Raman scattering, mid-infrared (molecular vibrations) and near-infrared (free carrier) absorption, X-ray photoemission spectroscopy (XPS), electrical conductivity, conductive atomic force microscopy (cAFM). We determined effect actual Cu content on phonon spectra, spectral parameters plasmon band. An increase conductivity NC upon annealing...
Size-selected series of copper-deficient colloidal Cu–In–S quantum dots (QDs) stabilized with glutathione are obtained by the exchange reaction in aqueous solutions under mild synthesis conditions. The optical bandgap and photoluminescence maximum position shift toward higher energies decreasing QD size. Based on X-ray diffraction data, QDs assigned to a tetragonal chalcopyrite-type structure. average size QDs, estimated from Scherrer formula comparison absorption edge-based sizing curves,...
Experimental Raman scattering study of mixed Ag x Ga Ge 1− Se 2 (0.167 ≤ 0.333) single crystals is reported. The spectra transformation upon composition variation exhibits the two‐mode type behavior, with lines end‐member compounds solid solution (AgGaSe and GeSe ) dominating in spectra, whose relative intensities vary composition.
We introduce a new concept of "bottom-to-top" design intercalate carbon nitride compounds based on the effects self-assembly colloidal single-layer (SLCN) sheets stabilized by tetraethylammonium hydroxide NEt4OH upon ambient drying water solvent. These include (i) formation stage-1 intercalates during SLCN colloids glass substrates and (ii) spontaneous layered hexagonally-shaped networks freshly-cleaved mica surfaces. The dynamics was followed in situ X-ray diffraction allowing different...
Ag–(In,Ga)–S quantum dots (QDs) were obtained by colloidal synthesis from aqueous solutions with different [In]/[Ga] precursor ratios in the presence of glutathione ligands under mild conditions. Size-selected fractions separated repeated centrifuging addition 2-propanol. The QD chemical composition determined X-ray photoelectron spectroscopy is noticeably In-enriched respect to ratio. size estimated halfwidth diffraction peaks for non-fractioned about 2 nm. synthesized QDs reveal a shift...
Phonon spectra of two novel nonlinear optical crystals, PbGa 2 GeSe 6 and GeS , are studied experimentally by Raman infrared reflection spectroscopy theoretically density functional theory (DFT) lattice dynamics calculations. The experimental peak frequencies compared with calculated vibration frequencies, a very reasonable agreement is established. A comparative analysis results for earlier reported data on relevant binary ternary metal chalcogenides clearly indicates that the similarity...
The problem with waste heat in solar panels has stimulated research on materials suitable for hybrid cells, which combine photovoltaic and thermoelectric properties. One such potential material is Cu2ZnSnS4 (CZTS). Here, we investigated thin films formed from CZTS nanocrystals obtained by "green" colloidal synthesis. were subjected to thermal annealing at temperatures up 350 °C or flash-lamp (FLA) light-pulse power densities 12 J/cm2. range of 250-300 was found be optimal obtaining...
The subject of analysis is methods and means unique identification objects in geospatial datasets, created, registered used geographic information systems for various purposes territorial coverage. Systems are classified according to basic technologies the presence semantic content composition identifiers, particular, these based on use of: 1) universal identifiers such as UUID; 2) direct geocoding using object coordinates; 3) indirect names addresses. advantages limitations each three...
Abstract Recently, methane has been demonstrated as an effective n -type dopant for ZnO thin films deposited using the RF-magnetron sputtering method. It was shown that major electrical doping effect of is caused by hydrogen released during decomposition. This work investigates origin observed increase in conductivity methane-doped with thickness. The study aimed at describing nature this thickness-dependent through a detailed analysis morphology and crystalline structure. A combination...
Sreekanth Mandati opened a general discussion of one the papers by Susanne Siebentritt: If full width at half maximum (FWHM) PL peak is larger, quasi Fermi level splitting (qFls) accurate (https://doi.org/10.1039/d2fd00057a)? What if we have shoulder peaks? S