N. E. A. Azhar

Structural and electrical properties of nanostructured TiO 2 thin film at low molarity

Titanium dioxide, TiO2 is a semiconductor material which has many useful properties. This paper is to clarify the use of sol-gel method in the production of nanostructured TiO2. Since sol-gel method is quite simple to compare with sputtering or pyrogenic process. The solution concentration will be varied in low molarity of 0.06M, 0.04M and 0.02M. Spin coating was used to deposit the nanostructured TiO2 on to the glass substrate and the surface morphology was observed using the Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The electrical properties were investigated by using two probe current-voltage (I-V) measurements to study the electrical resistivity behavior hence the conductivity of the film. Based on the result, higher the molarity of TiO2, the surface become more uniform and the IV becomes much better. The best thin film characteristic by low molarity parameter from 0.06M, 0.04M, 0.02M and 0.01M is the one with lowest molarity of 0.01M thin film.

Nanostructured Al-doped ZnO-based gas sensor prepared using sol-gel spin-coating method

Nanostructured Aluminium (Al) doped zinc oxide (ZnO) was prepared using sol-gel spin-coating method. These films were tested under different exposure of oxygen flow rates at room temperature with bias voltage applied at 5 V. The structural properties were characterized using Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The fesem image revealed the surface morphology of nanostructured ZnO. The diameters size of nanostructured Al-doped ZnO thin film was observed in range of 16-46 nm. These thin films were tested for oxygen-sensing characteristic by varying the gas flow rates at room temperature. The nanostructured Al-doped ZnO-based gas sensor exhibited good sensitivity at low flow rates of oxygen exposure.

Effect of TiO2 thickness on nanocomposited aligned ZnO nanorod/TiO2 for dye-sensitized solar cells

The TiO2 films were deposited on glass substrate at different thicknesses with different deposition frequencies (1, 2, 3 and 4 times) using spin coating technique and their structural properties were investigated. Subsequently, the nanocomposited aligned ZnO nanorods and TiO2 were formed by deposited the TiO2 on top of aligned ZnO Nanorod on ITO-coated glass at different thicknesses using the same method of TiO2 deposited on glass substrate. The nanocomposited aligned ZnO nanorod/TiO2 were coated with different thicknesses of 900µm, 1815µm, 2710µm, 3620µm and ZnO without TiO2. The dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2 with thickness of 900µm, 1815µm, 2710µm and 3620µm and ZnO without TiO2 and their photovoltaic properties of the DSSCs were investigated. From the solar simulator measurement the solar energy conversion efficiency (η) of 2.543% under AM 1.5 was obtained for the ZnO nanorod/TiO2 photoanode-2710µm Dye-Sensitized solar cell.

Electrical and structural properties of nanotetrapod zinc oxide thin films prepared with different deposition temperature

Nanotetrapod zinc oxide (ZnO) thin films have been deposited by thermal chemical vapor deposition (TCVD) technique. The films were deposited at 700°C and 800°C to study the temperature effect of physical properties of the nanotetrapod ZnO thin films. From XRD result shows the highest peak can observed from sample 700°C at (002) orientation. It was found that the size of nanotetrapod increased with increased of deposition temperature. The energy dispersive X-ray spectrometer (EDX) spectrum shows that the grown product contains zinc and oxygen only. At 800°C show the minimum of resistivity for the thin film which is 1.10 ohm. cm. Photoluminescence measurement shows a sharp peak ultraviolet emission at 380 nm and high intensity visible peak at 700°C because of defect due to oxygen vacancy and crystallization of ZnO nanotetrapod.

The effect of different concentration of TiO2 in solution prepared by sol-gel method on morphology and I-V characteristics for organic solar cell applications

TiO2 is a well-known material especially for potential applications in organic solar cells. In this research the objective was to achieve high current-voltage (I-V) characteristics that will improve electron migration. The nanostructured TiO2 was deposited onto a glass substrate using the well-known sol-gel spin coating method. Eight TiO2 solutions with different molarity were tested for their performance as the electron conductor layer in organic solar cells. The surface topology and morphology of nanostructured TiO2 was observed using AFM and FESEM. The electrical properties were investigated by using two probe I-V measurements to study the electrical resistivity behaviour, hence the conductivity of the film. The results showed the lower the molarity of TiO2, the more uniform is the surface achieved, and the better the I-V characteristics for solar cell application. As predicted, the best thin film characteristic is the 0.01M concentration which will be applied in future organic solar cell work.

Effect of Nb-doped TiO2 on nanocomposited aligned ZnO nanorod/TiO2: Nb for dye-sensitized solar cells

The Nb-doped TiO2 films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO2 films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO2 (TiO2:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO2:Nb-5at.%.

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement shows that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.

Investigation of electrical and optical properties of MEH-PPV: ZnO nanocomposite films for OLED applications

Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. The optical and electrical of nanocomposite films based on poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanostructured of various deposition layers (1 to 3 layers) have been investigated. The MEH-PPV: ZnO nanocomposite films were deposited using spin-coating technique. The surface morphology nanocomposite films were characterized using field emission scanning electron microscope. From surface profiler measurement, we found that the thickness of nanocomposite films increased as deposition time increased. The optical properties were measured using photoluminescence spectroscope. The photoluminescence (PL) spectra showed that two deposition layers is the highest intensity at visible region (green emission) due to high energy transfer from particles to the polymer. The current density for two layers sample is...

Annealing temperature and spin speed effect on TiO2 nanostructured topology and electrical properties

TiO2 were deposited by using one of the sol-gel methods, the spin coating method. The speed of the spin coater used can be adjusted up to 8000rpm, but in this study only 1000rpm, 2000rpm and 3000rpm was used. There are 3 level of speed with different annealing temperature to provide a fine differentiation in between each parameter. These parameters will be characterized by current-voltage (I-V), Atomic Force Microscopy (AFM), UltraViolet-Visible spectrophotometry (UV-Vis) and RAMAN spectroscopy. As further discovered, lower rpm have quite a thick film that it could not be characterized by AFM, that makes some of the samples did not have AFM characterization. The highest point of the current at 10V in the IV graph is at 1000rpm spin speed and annealed at 425°C temperature of 6.1E-8 which then makes it the highest in conductivity at 5.39E+5.

Effect of time deposition to the optical properties of ZnO nanotetrapods for OLED applications

Zinc Oxide (ZnO) is a metal oxide semiconductor that used for organic light emitting diode (OLEDs) applications. The ZnO nanotetrapods nanotetrapod of various time depositions has been synthesized using thermal chemical vapor deposition (thermal-CVD) method. In this study, the synthesizations were deposit at 30 minutes and 50 minutes to investigate the time deposition effect of ZnO nanotetrapods. The optical properties were obtained using photoluminescence (PL). The PL spectra show that the sample at 30 minutes is the highest intensity for ultraviolet (UV) emission due to crystallization of ZnO nanotetrapods. X-Ray Diffraction was deposited using Broker AXS D8 Advance with Cu Kα radiation. It is show the highest peak can observe for sample 30 minutes. From FESEM images, it was found that the length of ZnO nanotetrapods increased with increased of time deposition.