Advanced Materials Research Vol. 667

Abstract: Thin films of poly [2-methoxy-5(2’-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV) prepared from aromatic and non-aromatic solvents were obtained by spin coating techniques. The non-aromatic solvents used are chloroform and tetrahydrofuran (THF), while the aromatic solvents used are toluene and xylene. The UV-Vis and PL spectra of MEH-PPV thin films prepared from toluene and xylene slightly red shift compared to thin films from chloroform and THF. The shifting due to the aggregation formed in thin films. The SEM images of thin films prepared from aromatic solvents shows smooth surface while surface of thin films from non-aromatic is rough. The FTIR spectra of all samples show the same peak assignment of MEH-PPV.

Abstract: ZnO nanorods were successfully grown on Au coated Si substrate and Si bare substrate. The growth was using sol-gel immersion method at different deposition time which is 2, 4, 6, 8, 10 and 12 hours. In the presence of Au, growth rate of nanorods is much faster as it performs as a catalyst by decreasing the growth time of ZnO nanorods to half compared to growth on Si substrate without Au coated. Using Scanning Electron Microscope (SEM), changes in growth of nanorods at different deposition time was captured and the structural properties are discussed.

Abstract: Carbon nanotubes (CNTs) were deposited on silicon wafer (Si) by Thermal Chemical Vapor Deposition (TCVD). The new starting material of fermented tapioca was used as carbon source. The gas flow of Argon (Ar) was constant at 70 bubbles per minute and 20 minutes of deposition time. Before the deposition process, the silicon wafer was coated with Nickel catalyst using spin coater. Various parameters such as vaporization temperature and deposition temperature have been studied. Surface morphology and uniformity were characterized using FESEM. The CNTs were structurally characterized using FESEM at different magnification to see the differences of CNTs growth at different temperature of the starting material. The surface morphology and uniformity of CNTs were dependent to parameters.

Abstract: In this paper we address sensitivity of SnO2 thin film deposited by thermal chemical vapor deposition in terms of its behavior towards humidity variations. The structural, optical and electrical properties of SnO2 thin film deposit at different substrate temperature grown by thermal chemical vapor deposition (CVD) are also reviewed. FESEM image reveal smallest particle size of SnO2 at substrate temperature 500°C. Pl measurement shows red shift of SnO2 at substrate temperature 500°C. All thin film performing slightly linear sensitivities towards relative humidity (RH%).

Abstract: Carbon nanotubes (CNTs) were deposited on silicon wafer (Si) by Thermal Chemical Vapor Deposition (TCVD). The new starting material of camphor oil was used as carbon precursor. The gas flow of Argon (Ar) was constant at 100 bubbles per minute and 30 minutes of deposition time. Before the deposition process, silicon was coated with mixture of nickel (II) nitrate hexahydrate, Ni (NO3)2.6H2O and ethyl alcohol, C2H5OH using spin coater. Variable parameter which is deposition temperature has been studied. Chemical functional groups of carbon nanotubes were characterized using FTIR while surface morphology and uniformity were characterized using FESEM. The FTIR result shows peaks attributed to multi–walled carbon nanotubes (MWCNT) vibration modes.

Abstract: Effect of PEG on the TiO2 electrode morphology for scattering enhanced properties of the modified paste containing TiO2 sol-gel mixed with Degussa P-25 were investigated. The high surface area of the scattering centres in this study were formed by using nano size particles ascribed from TiO2 sol-gel while the sub-micron size particles were utilized from the reaction of PEG on the Degussa P-25 particles. The pore size distributions were tailored by varying the PEG content in the fabricated electrodes. Higher surface area with adequate pore size of P30 electrode has contributed to higher JSC and efficiency (η) of 11.35450 mA/cm2 and 2.479624 %, respectively. Photocurrent action spectra of IPCE of the DSSC exhibit the maximum of 42 % at 550 nm correspond to the P30 TiO2 electrode. Overall results suggest that the incorporation of TiO2 sol-gel component mixed with TiO2 paste derived from commercially available nanopowder could enhance surface area as well as serves for better light scattering effect, while PEG addition creates adequate pore size distribution to maximize the dye adsorbed on the TiO2 electrode.

Abstract: The effects of temperature on carbon nanotubes (CNTs) by thermal chemical vapor deposition (TCVD) method were systematically studied. Natural hydrocarbon source; palm oil was used as precursor and argon as carrier gas. Palm oil vaporized optimally at 450oC in ambient pressure. The synthesis temperature start at 650°C and were increased at rate of 50°C for series of samples until it reaches maximum temperature of 900°C. The samples were grown on nickel nitrate, which was coated on silicon substrate. The CNTs characteristics were studied using field emission scanning electron microscopy (FESEM), Raman and infrared (IR) spectroscopy. The experimental results revealed that CNTs properties are highly dependent on temperature. It was found that with increasing synthesis temperature, the CNTs diameter decreased initially and then increased after passing an optimum synthesis temperature of 750°C. The bamboo like structure were obviously found at higher synthesis temperature 800°C-850°C while there were few CNTs seen at 900°C.

Abstract: Titanium dioxide nanowires have successfully prepared by hydrothermal method. The effect of hydrothermal growth temperature on the morphology and structural properties of TiO2 nanowires have been investigated. It was observed that at low temperature of 100 °C, the formation of nanowires was at early stage, while hydrothermal treatment at 130 °C showed the TiO2 precursor acquired enough energy for formation of the nanowires. Increased the temperature to 200 °C was formed the bundle of nanowires in microsize. The diameter of nanowires increased as the temperature increased. The TiO2 nanowires produced at temperature of 150 °C and annealed at 500 °C showed highest crystallinity with anatase phase.

Abstract: Solid state dye-sensitized solar cells (DSSCs) were first reported in 1991 without employing p-type as hole conductor. The p-type as hole conductor was first introduced in 1995 and CuI is preferred among others p-type semiconductors. However, in 2003 utilizing of CuI based DSSC was found unstable by the excessive iodine strongly decreased the photocurrent of the cell. Later then, the stability of CuI based DSSCs was reported can be improved by added small amount of triethylamine hydrothiocyanate (THT) in the CuI coating solution. Following to that, in this work new chemical is introduce as an option to present situation which can give equally or better effective for fabrication of solid-state DSSCs. The chemical is called tetramethylethylenediamine (TMED), is employed to CuI in sol-gel process and their characterizations have been studied. The CuI coating solution was prepared by dissolved CuI powder with acetonitrile and added in 0.5mL TMED. Using spin coating technique the sol then deposited onto glass and silicon substrate at room temperature. The film were analyzed by their particles conductivity using pH meter, surface morphology using Field Emission Scanning Electron Microscope (FE-SEM) and optical properties using ultraviolet visible spectroscopy (UV-Vis) and photoluminescence (PL) measurement. The results of this sol-gel were compared with other CuI sol-gel which prepared by dissolved CuI powder with acetonitrile only. The optical transmittance within ultra-violet range exhibited that thin film is transparent and it optical band gap have been studied. Further clarification and measurements need to be done in order to prove that the proposed chemical can be used as an option.

Abstract: Titanium dioxide (TiO2) nanostructures were deposited on glass substrate by Radio Frequency (RF) magnetron sputtering. The samples deposited at various sputtering pressures and annealed at 723 K, were characterized using Atomic Force Microscope (AFM) to observe the surface morphology and topology, roughness properties and cross-sectional of TiO2 nanostructures, Field Emission Scanning Electrons Microscope (FESEM) to observe the particle sizes of TiO2 nanostructures and UV-vis spectroscopy to record the UV-vis transmission spectra. The aim of this paper is to determine which parameter of sputtering pressures influence the optimization of TiO2 nanostructures. AFM images show that the surface roughness of the samples decreases as the working pressures of sputtering increases. From FESEM images, it can be deduced that the higher the sputtering pressure, the smaller the particle size is. All the samples are highly transmittance with an average transmittance higher than 80% in the visible region as recorded by UV-vis transmission spectra. The relatively high transmittance of the sample indicates its low surface roughness and good homogeneity. For optimum TiO2 nanostructures deposited at various RF pressures it has the lowest surface roughness and the smallest TiO2 size particles with the indirect optical band gap of 3.41 eV.