In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous sol... more In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous solutions containing ZnCl2 and thiocarbamide (tu) at different molar ratios. It has been observed that addition of thiocarbamide into the spray solution has great impact on the size, shape and phase composition of the ZnO crystals. Obtained layers were characterized by scanning electron microscopy (SEM) equipped with energy selected backscattered electron detection system (ESB), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). Small addition of thiocarbamide into ZnCl2 solution (ZnCl2:tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl2 solution. Diameter of ZnO rods decreases from 270 to 100 nm and aspect ratio increases from ~2.5 to 12 spraying ZnCl2 and ZnCl2:tu solutions, respectively. According to XRD, well crystallized (002) orientated pure wurtzite ZnO crystals have been formed. However,...
In the present study nanostructured solar cells were prepared by in-line spray pyrolysis techniqu... more In the present study nanostructured solar cells were prepared by in-line spray pyrolysis technique. ETA cells were realized on ZnO nanorod layer using CuInS2 as an absorber material. Thin layers of TiO2 or indium sulfide (In-S) were deposited by spray onto ZnO nanorods in order to prevent the ZnO crystals from dissolution during the deposition of acidic solutions to form the next layers of the cell. Insertion of both TiO2 and In-S layers into the cell structure reduces the electrical shorts between front and back contact. Thickness of TiO2 layer should be carefully controlled as at certain thickness it blocks the charge carrier transport in the device. The use of structured layer with ZnO nanorods (L~ 500 nm) increases the current density from 5-6 mA/cm2 up to 11-14 mA/cm2 with no significant reduction in Voc and FF compared to the planar device. Further increasing of the rod length leads to the higher current densities but decreases the open circuit voltage due to increased recombination at higher interface area. The conversion efficiency of 3.9 % (Voc=463 mV, j=14 mA/cm2, FF=60%) is obtained for the structure TCO/ZnO(rod)/barrier/In2S3/CuInS2/PEDOT:PSS prepared at very low cost.
The experimental research into the aqueous photocatalytic oxidation of doxycycline, a tetracyclin... more The experimental research into the aqueous photocatalytic oxidation of doxycycline, a tetracycline family antibiotic, was undertaken. The objective of the study was to ensure the feasibility of doxycycline photocatalytic degradation by UVA irradiated titania coatings on granulated media to be used in fluidised bed photocatalytic reactor and by slurries of P25, Evonik, as well as by visible light-sensitive sol-gel synthesized carbon-containing titania. The parameters influencing doxycycline oxidation, like catalyst concentration, initial doxycycline concentration and pH with P25 TiO
The cost-effective spray pyrolysis technique was applied to prepare ZnS thin films for large-scal... more The cost-effective spray pyrolysis technique was applied to prepare ZnS thin films for large-scale applications. Aqueous solutions containing ZnCl2 and SC(NH2)2 were deposited onto glass and n-type Si(100) substrates at 430-600°C. The structure and phase composition were studied by XRD and FTIR, the surface morphology by SEM. The optical properties were determined from the transmittance and reflectance measurements in the UV-visible and near-IR regions. The phase composition, crystallinity, and surface morphology of the films could be controlled by the Zn : S molar ratio in the stock solution and the deposition temperature. Highly (001) oriented ZnS films with wurtzite structure were grown at temperatures above 500°C using the Zn:S molar ratio 1 :2 in the solution. The sprayed films had high optical transmittance in a wide spectral range and the refractive index of up to 1.9 at 632.8 nm. It was also found that the sprayed ZnS films are capable of being used as antireflection coatings in Si-based devices.
ABSTRACT The In(OH)xSy thin films were deposited by chemical bath deposition (CBD) using three di... more ABSTRACT The In(OH)xSy thin films were deposited by chemical bath deposition (CBD) using three different deposition procedures: ‘hot’: starting the deposition at 70 °C, ‘cold’: starting the deposition at room temperature and pre-treatment with In3+ ions prior the ‘hot’ deposition. The analysis of the deposited In(OH)xSy layers on glass revealed that modifications in the chemical bath deposition procedure provoked significant changes in the nucleation process, the growth rate, the layer elemental composition and the layer morphology. With an additional In3+ pre-treatment or starting from a cold solution, the formation of a dense bottom layer has been observed, resulting in In(OH)xSy films with more compact structure with refractive index values of 2.6. The comparison of the measured In/S ratio with a thicker layer suggests, that the In(OH)xSy deposition starts with an OH-rich layer. Assuming the indirect allowed band gap transition type, an Eg of 2.2 eV was found independent of the procedure type or deposition time.
ABSTRACT ZnO nanorods were prepared by a spray pyrolysis technique on both as-received and etched... more ABSTRACT ZnO nanorods were prepared by a spray pyrolysis technique on both as-received and etched Indium Tin Oxide (ITO)/glass substrates. The morphologies of the ITO substrates, the ZnO nucleation mechanism and the development of ZnO nanorods on both types of ITO substrates were investigated by Atomic Force Microscopy and Scanning Electron Microscopy methods. It was found that the amount of nucleation sites on as-received ITO is significantly higher compared to that on the etched ITO. As a result, well-shaped, elongated, strongly c-axis-oriented ZnO nanorods were obtained on the etched ITO/glass substrates. In contrast, randomly oriented ZnO nanocrystals with different shapes and sizes, as well as low aspect ratios, were obtained on the as-received substrates. It was found that ZnO nucleation follows the grain-boundary nucleation mechanism.
The ZnS layers morphology, structure, composition, and optical properties were investigated with ... more The ZnS layers morphology, structure, composition, and optical properties were investigated with respect to the precursors (zinc chloride and thiocarbamide, Zn:S) molar ratio in spray solution (1:1, 1:2, and 1:3) and growth temperatures in the range of 400–600 °C. Scanning electron microscopy (SEM), X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDX), UV–VIS, and PL spectroscopy were applied to characterize the ZnS layers. Layers obtained at temperatures up to 450 °C are not well crystallized and contain residues originated from undecomposed precursors. ZnS films become crystalline at Ts = 500 °C. Layers grown from 1:1 solution at 550 °C are mixture of ZnS and ZnO phases, whereas at 600 °C layers of ZnO were obtained. Films produced from 1:2 solution at 500–600 °C are of ZnS with a wurtzite structure and Eg of 3.66 eV, but contain traces of ZnO phase when grown at 550 or 600 °C. Appearance of ZnO phase in the films grown from 1:1 and 1:2 solutions is explained by the res...
In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous sol... more In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous solutions containing ZnCl2 and thiocarbamide (tu) at different molar ratios. It has been observed that addition of thiocarbamide into the spray solution has great impact on the size, shape and phase composition of the ZnO crystals. Obtained layers were characterized by scanning electron microscopy (SEM) equipped with energy selected backscattered electron detection system (ESB), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). Small addition of thiocarbamide into ZnCl2 solution (ZnCl2:tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl2 solution. Diameter of ZnO rods decreases from 270 to 100 nm and aspect ratio increases from ~2.5 to 12 spraying ZnCl2 and ZnCl2:tu solutions, respectively. According to XRD, well crystallized (002) orientated pure wurtzite ZnO crystals have been formed. However,...
In the present study nanostructured solar cells were prepared by in-line spray pyrolysis techniqu... more In the present study nanostructured solar cells were prepared by in-line spray pyrolysis technique. ETA cells were realized on ZnO nanorod layer using CuInS2 as an absorber material. Thin layers of TiO2 or indium sulfide (In-S) were deposited by spray onto ZnO nanorods in order to prevent the ZnO crystals from dissolution during the deposition of acidic solutions to form the next layers of the cell. Insertion of both TiO2 and In-S layers into the cell structure reduces the electrical shorts between front and back contact. Thickness of TiO2 layer should be carefully controlled as at certain thickness it blocks the charge carrier transport in the device. The use of structured layer with ZnO nanorods (L~ 500 nm) increases the current density from 5-6 mA/cm2 up to 11-14 mA/cm2 with no significant reduction in Voc and FF compared to the planar device. Further increasing of the rod length leads to the higher current densities but decreases the open circuit voltage due to increased recombination at higher interface area. The conversion efficiency of 3.9 % (Voc=463 mV, j=14 mA/cm2, FF=60%) is obtained for the structure TCO/ZnO(rod)/barrier/In2S3/CuInS2/PEDOT:PSS prepared at very low cost.
The experimental research into the aqueous photocatalytic oxidation of doxycycline, a tetracyclin... more The experimental research into the aqueous photocatalytic oxidation of doxycycline, a tetracycline family antibiotic, was undertaken. The objective of the study was to ensure the feasibility of doxycycline photocatalytic degradation by UVA irradiated titania coatings on granulated media to be used in fluidised bed photocatalytic reactor and by slurries of P25, Evonik, as well as by visible light-sensitive sol-gel synthesized carbon-containing titania. The parameters influencing doxycycline oxidation, like catalyst concentration, initial doxycycline concentration and pH with P25 TiO
The cost-effective spray pyrolysis technique was applied to prepare ZnS thin films for large-scal... more The cost-effective spray pyrolysis technique was applied to prepare ZnS thin films for large-scale applications. Aqueous solutions containing ZnCl2 and SC(NH2)2 were deposited onto glass and n-type Si(100) substrates at 430-600°C. The structure and phase composition were studied by XRD and FTIR, the surface morphology by SEM. The optical properties were determined from the transmittance and reflectance measurements in the UV-visible and near-IR regions. The phase composition, crystallinity, and surface morphology of the films could be controlled by the Zn : S molar ratio in the stock solution and the deposition temperature. Highly (001) oriented ZnS films with wurtzite structure were grown at temperatures above 500°C using the Zn:S molar ratio 1 :2 in the solution. The sprayed films had high optical transmittance in a wide spectral range and the refractive index of up to 1.9 at 632.8 nm. It was also found that the sprayed ZnS films are capable of being used as antireflection coatings in Si-based devices.
ABSTRACT The In(OH)xSy thin films were deposited by chemical bath deposition (CBD) using three di... more ABSTRACT The In(OH)xSy thin films were deposited by chemical bath deposition (CBD) using three different deposition procedures: ‘hot’: starting the deposition at 70 °C, ‘cold’: starting the deposition at room temperature and pre-treatment with In3+ ions prior the ‘hot’ deposition. The analysis of the deposited In(OH)xSy layers on glass revealed that modifications in the chemical bath deposition procedure provoked significant changes in the nucleation process, the growth rate, the layer elemental composition and the layer morphology. With an additional In3+ pre-treatment or starting from a cold solution, the formation of a dense bottom layer has been observed, resulting in In(OH)xSy films with more compact structure with refractive index values of 2.6. The comparison of the measured In/S ratio with a thicker layer suggests, that the In(OH)xSy deposition starts with an OH-rich layer. Assuming the indirect allowed band gap transition type, an Eg of 2.2 eV was found independent of the procedure type or deposition time.
ABSTRACT ZnO nanorods were prepared by a spray pyrolysis technique on both as-received and etched... more ABSTRACT ZnO nanorods were prepared by a spray pyrolysis technique on both as-received and etched Indium Tin Oxide (ITO)/glass substrates. The morphologies of the ITO substrates, the ZnO nucleation mechanism and the development of ZnO nanorods on both types of ITO substrates were investigated by Atomic Force Microscopy and Scanning Electron Microscopy methods. It was found that the amount of nucleation sites on as-received ITO is significantly higher compared to that on the etched ITO. As a result, well-shaped, elongated, strongly c-axis-oriented ZnO nanorods were obtained on the etched ITO/glass substrates. In contrast, randomly oriented ZnO nanocrystals with different shapes and sizes, as well as low aspect ratios, were obtained on the as-received substrates. It was found that ZnO nucleation follows the grain-boundary nucleation mechanism.
The ZnS layers morphology, structure, composition, and optical properties were investigated with ... more The ZnS layers morphology, structure, composition, and optical properties were investigated with respect to the precursors (zinc chloride and thiocarbamide, Zn:S) molar ratio in spray solution (1:1, 1:2, and 1:3) and growth temperatures in the range of 400–600 °C. Scanning electron microscopy (SEM), X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDX), UV–VIS, and PL spectroscopy were applied to characterize the ZnS layers. Layers obtained at temperatures up to 450 °C are not well crystallized and contain residues originated from undecomposed precursors. ZnS films become crystalline at Ts = 500 °C. Layers grown from 1:1 solution at 550 °C are mixture of ZnS and ZnO phases, whereas at 600 °C layers of ZnO were obtained. Films produced from 1:2 solution at 500–600 °C are of ZnS with a wurtzite structure and Eg of 3.66 eV, but contain traces of ZnO phase when grown at 550 or 600 °C. Appearance of ZnO phase in the films grown from 1:1 and 1:2 solutions is explained by the res...
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