Influence of substrate annealing on inducing Ti3+ and oxygen vacancy in TiO2 thin films deposited via RF magnetron sputtering

Nano-crystalline TiO2 has been prepared by RF magnetron sputtering at varied substrate temperatures ranging from 200 to 500 °C. The alteration of oxygen and titanium atom in TiO2 at uppermost surface is clearly observed on the effect of annealing temperature by Auger Electron Spectroscopy (AES) technique. The measurement of peak to peak value of Ti and O transition line at 400 °C indicates the surface chemical state of O2 in TiO2 thin films defect at surface and Fermi level was analyzed using the X-Ray Photoelectron Spectroscopy (XPS). The Ti 2p observation of pre and post surface treatment shows the concentration of Ti3+ is seven times higher after post sputtered for sample 200 °C. Ti3+ decrease by increasing temperature. The Ti3+-oxygen vacancy which also assigned as Ti2O3 occurred in all sample, yet sample deposited at 400 °C gives nearest binding energy for Ti2O3. This observation also supported by The Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analysis which shows highest total ion count for positive polarity is O+ for sample at 300 °C and Ti ion dominant is Ti2O3 + for sample at 400 °C. Based on the analyses, it is clearly seen that high defect of Ti3+-oxygen vacancy which is located between surface layer and fermi level state, this defect levels was created at surface layer at low annealing temperature. However, increasing temperature leads to defect creation on bellow surface layer which consider as within fermi level laye

A wideband reflectarray antenna based on organic substrate materials

Significant improvements in terms of bandwidth of reflectarray antennas have been achieved by introduction of innovative paper substrate dielectric materials. Three differently custom composed organic dielectric substrates have been characterized for dielectric properties using a broadband technique based on open ended coax cable method. The substrates show low dielectric permittivities of 1.81, 1.63 and 1.84 along with a loss tangent of 0.053, 0.047 and 0.057. Validation of using the proposed substrates for reflectarray antenna was done by modelling and fabricating reflectarray unit elements on the three substrates. Scattering parameter analysis of unit reflectarray elements show encouraging results with a broadband frequency response of 340 MHz at a phase gradient of 0.14 º/MHz. Thus the proposed substrate could serve exceptionally to address the narrow bandwidth problem in reflectarray antennas

Zinc Oxide Nanostructures for Efficient Energy Conversion in Organic Solar Cell

We present a new approach of solution-processed using zinc oxide (ZnO) nanostructures as extraction layer material for organic solar cells. It is low chemical reaction compatibility with all types of organic blends and its good adhesion to both surfaces of ITO/glass substrate and the active layer (blends). Parameters such as the thickness and the morphology of the films were investigated to prove that these factors greatly affect the efficiency of organic solar cells. In this work, ZnO layer with thickness of approximately 53 nm was used as an interlayer to prevent pin-holes between the electrode and the polymer layer. The polymer layer was coated on the ZnO layer with the thickness of about 150 nm. The thick polymer layer will form a non-uniform surface because of the solvent, 1-2dichlorobenzene will etch away some region of the polymer layer and forming pin-holes. ZnO nanostructures layer was used to prevent pin-holes between the polymer layer and electrode. From the surface morphology of ZnO layer, it shows a uniform surface with particle grain size obtained between 50 -100 nm. The presence of the interlayer has a positive effect on the electrical characteristics of the solar cells. It was found that an organic solar cell with thickness less than 150 nm shows the optimum performance with efficiency of 0.0067% and Fill Factor (FF) of about 19.73

Performance of Dye-Sensitized Solar Cell Using Size-Controlled Synthesis of TiO2 Nanostructure

Titanium dioxide (TiO2) or titania shows a great interest in solar cell application due to its morphology and crystalline structure. Moreover, it is an affordable compound that could make solar cells more cost economical than traditional silicon solar cells. In this study, one-step hydrothermal method is demonstrated to synthesis rutile TiO2 nanorods and nanoflowers morphology in nanoscale dimension on different hydrothermal reaction times for Dye-sensitized solar cells application. Increasing the reaction time could influence in formation of higher crystalline rutile phase titania nanostructure before abruptly decreases as the prolong hydrothermal process carry out. The length of the nanorods produced shows increasing behaviour and the growth of nanoflowers are become denser obviously. Band gap estimation is 2.75 eV slightly lower than bulk rutile TiO2. It shows that the growth mechanism under different reaction times has great influences on the morphologies and alignment of the nanostructure. Further, the DSSCs fabricated using 15 hours reaction time exhibited the best photovoltaic performance with highest efficiency of 3.42% and highest short-circuit photocurrent of 0.7097V

Fabrication Of TiOâ‚‚ Nanoflowers Powder with Various Concentration Of CTAB

Nanostructures titanium dioxide (TiOâ‚‚) such as nanoflowers and nanorods have contribute in many application. Among TiOâ‚‚ nanostructures, TiOâ‚‚ nanoflowers gives high surface area that contribute in good binding properties and reducing internal stress and increasing strength of the ceramics.This paper presents fabrication of TiOâ‚‚ nanoflowers powder to overcome the cracking problem in ceramic industry. In this study, fabricated rutile-phased TiOâ‚‚ nanoflower powder has been successfully synthesized by using hydrothermal method and the surface morphology, structural properties, and the composition of TiOâ‚‚ nanoflower powder also identified. The fabricated TiOâ‚‚ are characterized using Field Emission Scanning Electron Microscopy (FESEM) to observe the surface morphology of TiOâ‚‚, X-ray Dispersion (XRD) was used to determine the crystallite phase and EDX for element composition in fabricated TiOâ‚‚ powder. The synthesized TiOâ‚‚ powder was obtained from the reaction between deionized water (DI), hydrochloric acid (HCl), Titanium Butoxide (TBOT) and Cetyltrimethylammonium Bromide (CTAB). The hydrothermal temperature is 150  ÌŠC with fixed hydrothermal time of 10 hours. The parameters varied is the mass of surfactant used, CTAB. The hydrothermal method is proven suitable to fabricate semiconductor materials due to its advantages that parameters are easily modified and can be performed under closed system with low operational temperature. Increased amount of CTAB used make the gap between the nanorod become closer and stronger. The diffraction peaks of all sample hardly changed, but the intensity for each sample was enhanced as the mass of CTAB used increased. The structure also become well crystallined in rutile phase structure

Fabrication Rutile-Phased TiO2 Film with Different Concentration of Hydrochloric Acid Towards the Performance of Dye-Sensitized Solar Cell

In this study, one-step hydrothermal method is demonstrated to synthesis TiO2 double-layer structure by modifying the concentration of hydrochloric acid (HCl). The X-ray diffraction (XRD) pattern analysis suggested that the dominant peak is rutile phase. Interesting morphologies such as cauliflower, chrysanthemum flower or dandelion structures over the nanorods layer were revealed by FE-SEM images and showed substantial effects to the thin film performance. UV-vis absorption spectra of prepared TiO2 film is in UV limitation with band gap energy (Eg) range from 2.57eV to 3.0eV. The optimum photoelectric conversion efficiency of DSSC is 42.5% that exhibited the efficiency of 6.41% for the sample synthesized using equal proportion of de-ionized water and HCl amount or in another word in accordance of ratio 1:1. These results serve as a guidance principle for preparing high quality DSSC thin film

Dye-sensitized solar cell using pure anatase TiO2 annealed at different temperatures

The performance of pure anatase titanium dioxide (TiO2) annealed at different tempera-tures as photoanode in the application of dye-sensitized solar cell (DSSC) was investigated and discussed. All samples of TiO2 were deposited on fluorine-doped tin oxide (SnO2) on glass substrate using spray pyrolysis deposition (SPD) method. Characterizations of the DSSCs fabricated were executed on their surface morphology, structural property, and energy conversion efficiency. In the DSSC preparation, anatase TiO2 thin films, platinum (Pt), ruthenium-based dye N719 and DPMII triiodide couple electrolyte were used as pho-toanodes, cathode/counter electrode, dye sensitizers and liquid electrolyte, respectively. All of the TiO2 photoanodes were annealed at 300 ◦C, 400 ◦C and 500 ◦C with a set left without any heat treatment. The thickness of anatase TiO2 photoanodes measured were in between 23 �m and 41 �m. The power conversion efficiency of DSSCs performed under visible light with intensity of 100 mW/cm2 shows that DSSC with pure anatase phased TiO2 annealed at 500 ◦C as photoanode yields the highest efficiency of 3.25%

Heterojunction of SnO2 nanosheet/arrayed ZnO nanorods for humidity sensing

For the first time, a rutile phased tin oxide (SnO2) nanosheet was assembled onto a zinc oxide (ZnO) nanorod array to form SnO2 nanosheet/ZnO nanorod array heterostructure films (TSZR) using a two-step solution immersion method. This study offers a facile and effective path to grow a SnO2 nanosheet assembled layer on ZnO nanorod arrays with a varied density using a tin (II) chloride dihydrate precursor to achieve an optimum humidity sensing response through the SnO2 growth time from 1 to 5 h. The structural characteristics, electrical properties, and humidity sensing response of the heterostructure films were investigated using various characterization techniques, such as field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, a two-probe current-voltage measurement, and a humidity sensing response measurement system. The synthesized ZnO nanorods have an average diameter of 90 nm, while the grown SnO2 nanosheets have an average width of 20 nm. The humidity response performance of the films demonstrates a remarkable dependence on the SnO2 nanosheet assembled layer on the ZnO nanorod array film with the best humidity sensitivity of 754.4 at room temperature obtained for the 2 h-grown SnO2 nanosheet-based 2TSZR heterostructure sample. The 2TSZR sample also exhibited good stability over a four-cycle measurement and magnified current value of the humidity sensing response at a high operating temperature up to 60 °C. These investigations reveal that the TSZR heterostructure films are promising for humidity sensing devices with high sensitivity

Synthesis characteristics of Cu particulates in high-pressure magnetron sputtering plasmas studied by in situ laser-light scattering

This paper reports the temporal evolution, the dependence on the discharge conditions, and the spatial distribution of Cu particulates synthesized in high-pressure magnetron sputtering plasmas. The spatial distributions of the size and the density of particulates were examined with precision using a two-wavelength laser light scattering technique. We found that more than 50% of Cu particulates in the discharge space had sizes ranging between 100 and 175 nm. The absolute density of Cu particulate was on the order of 10^[7]-10^[9] cm^[-3]. Cu particulates had concentrated distributions in the boundary between the bright plasma and the dark region and in the region connecting to the anode of the magnetron sputtering source. The spatial distribution, the size distribution, and the density of Cu particulates were sensitively dependent on the discharge power and pressure