M.S.P. Sarah

A study on ohmic contact of different metal contact materials on nanostructured Titanium Dioxide (TiO 2 ) Thin Film

Three different type of materials i.e Au, Pt, and Pd have been investigated as metal contact on Titanium Dioxide (TiO2) thin films. These metal contacts have been deposited using sputter coating method. Meanwhile sol-gel spin coating method has been chosen to deposits TiO2 thin film. The ohmic contact characteristic of the three materials has been studied using Current-Voltage measurement.

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.

Preparation and Characterization of Nanostructured CuO Thin Films using Sol-gel Dip Coating

Nanostructured CuO thin films were deposited onto quartz substrates by sol-gel dip coating technique. The precursor solution was prepared by dissolving copper acetate powder into isopropanol with molarity of 0.25M. Preheating and annealing temperature were fixed at 250°C and 600°C respectively. This study focused on various film thicknesses by varying the frequent number of deposited layers. The effect of thickness on electrical, surface morphology and optical properties of CuO thin film were studied. The surface morphology was examined using field emission scanning electron microscopy (FE-SEM), surface profiler for thickness measurement, optical properties of CuO thin film were characterized by using ultraviolet- visible spectroscopy (UV-VIS) for transmittance and absorbance, and the electrical property was examined by using two point probes method. The films were found to be denser at higher film thickness due to lesser porous observed on the surface. The thickness of these CuO thin films varied from 87.14 – 253.58 nm and the direct band gap energy was observed in between 1.9 to 2.35 eV. Lowest resistivity was found for sample with a thickness of 253.58 nm.

Annealing temperature effect on nanostructured TiO 2 films

The synthesization of TiO2 sol-gel, by using titanium dioxide nano powder as precursor. In the production of nanostructured TiO2, the annealing temperature for the film is differed to clarify the use of different temperature in annealing the film, the best temperature to get a good mobility in the current flow can be found. There are 7 samples with different drying temperature and different annealing temperature. The one with the highest IV characterization will be fabricated as thin film in the organic solar cell as the metal oxide film. As further discovered that the as-deposited without annealing sample have a quite thick film that it could not be characterized by Atomic Force Microscopy (AFM). The highest point of the current at 10 V in the IV graph is 500 C annealing temperature of 6.06E-9 A which then makes it the highest in conductivity at 3.37E-6 Sm-1. The current-voltage (I-V) measurement is used to study the electrical resistivity behaviour, hence the conductivity of the film to suit organic solar cell application.

Photoconductivity of nanocomposited MEH-PPV: CNTs thin film for organic solar cells application

Our work focused on nanocomposite MEH-PPV: CNTs prepared by spin coating technique. The MEH-PPV which is in powder form (commercially available) was weighted and then dissolved in Toluene and stirred for 48 hours. Then, a small amount of CNTs were added to the MEH-PPV solution. It is sonicated for 1 hour to ensure that CNTs is well dispersed in the MEH-PPV solution. The addition of CNTs in the MEH-PPV solution yields a nanocomposite MEH-PPV:CNTs solution. The electrical properties of the thin films were studied to identify whether the nanocomposite thin films have ohmic capability or vice versa. Optical properties of the thin films were characterized using UV-VIS-NIR spectrophotometer. From the current-voltage characteristics it can be seen that there is no photo response when light is illuminated to the sample of MEH-PPV blend CNTs. The highest conductivity is at 2 wt% concentration of CNT with 100k Sm−1. It also gives the highest value of absorption spectra which is 0.25 for nanocomposite MEH-PPV: CNTs thin film.

Photoconductivity of MEH-PPV:TiO 2 nanocomposite thin film

In this research the photoconductivity of a hybrid nanocomposite thin film based on poly(2-methoxy-5-ethylhexyloxy-1,4-phenylene)vinylene (MEH-PPV) and anatase nanopowder TiO2 are studied. The MEH-PPV:TiO2 nanocomposite thin film deposited on a glass substrate have been prepared at different composition of TiO2 nanopowder (from 5wt% to 20wt%) by spin-coating method. The current-voltage (I–V) characteristics are measured by two point probe solar simulator measured in dark and under illumination. It was found that the photoconductivity showed increment in value as the composition of TiO2 increase in the polymer based solution. The optical characterization is carried out via UV-Visible absorption spectroscopy to investigate the absorbance and optical band gap.

Effect of solution concentration on MEH-PPV thin films

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

The characterization of copper oxide with different molar concentration using sol-gel spin coating

The objective of this research is to evaluate the effect of different molar concentration of the copper oxide (CuO) thin films deposited using spin-coating technique. The CuO thin films were deposited on 500μm quartz substrates. The molar concentration of CuO solutions used were 0.3M, 0.35M, 0.4M, 0.45M and 0.5M were prepared using sol-gel method. These solutions were formed by dissolving copper acetate powder into isopropanol, diethanolamine and polyethylene glycol. All samples were annealed at 600°C for 1 hour in a furnace. The electrical properties were measured by two point probe to check thin film resistivity. The electrical measurements showed that current increased with the concentration. The thicknesses were performed using the surface profiler while the surfaces morphology were characterized using Field Emission Scanning Electron Microscopy (FESEM). The films surfaces were smooth with uniformly distributed grains. The optical transmittances were measured using UV-Vis spectrometer and the reading decreased with concentration.

Effect of annealing temperature on characteristics of ZnO/CuO nanocomposite thin films

Nanoparticles ZnO/CuO composite was successfully prepared through a simple sol-gel spin coating technique. The annealing temperature was within the range of 400°C to 600°C to study its effect to the physical, optical and electrical properties to the thin films. Their characteristics were studied by field emission scanning electron microscopy (FESEM), Atomic Force Microscopy (AFM), UV-Vis spectroscopy and 2-point probes I-V measurement. The thickness and grain size increased with the annealing temperature. The direct optical bandgap observed were between 3.06 eV to 3.2 eV, which increased with the decreased of the annealing temperature. The highest conductivity was obtained for sample annealed at 400°C with a value of 0.61614 S/cm.

Increment on Grain Size of TiO 2 doped niobium chloride (NbCl 5 ) by sol-gel spin coating technique

In this work, we have successfully prepared TiO2 thin films doped with various concentration of NbCl5. The doping concentrations were varied from 0.0 mol%, 0.1 mol%, 0.2 mol%, 0.3 mol% and 0.4 mol%. The characterizations were done by means of electrical properties and surface morphology. The results show that as the concentrations of NbCl5 increased, current escalates. For surface morphology, the grain size of TiO2 thin films becomes larger when doping concentrations were increased. It shows that the I-V characteristic depends on the grain size as the doping concentration of NbCl5 varies. The optimized thin film in this work is 0.4 mol% of NbCl5.