M. Rusop

COPPER IODIDE THIN FILMS AS A p-TYPE ELECTRICAL CONDUCTIVITY IN DYE-SENSITIZED p-CuI|Dye|n-TiO2 HETEROJUNCTION SOLID STATE SOLAR CELLS

The transparent semiconducting copper iodide (CuI) films were deposited by pulsed laser deposition (PLD) and their structural and optoelectrical properties in the power output of TiO2|Dye|CuI cells are reported. These CuI films exhibited optical transmittance of over 80% in the wavelength range from 400 to 900 nm and a minimum resistivity of about 2 KΩ-cm. An efficient charge generation is observed through the illumination of the TiO2 layer of the fabricated p-CuI|Dye|n-TiO2 cells. The cells performances have been given in the current–voltage (I–V) working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm2, 25°C). The maximum short circuit photo current density (Jsc) of about 12.2 mA/cm2 and open circuit photo voltage (Voc) of about 480 mV were obtained for the TiO2|Dye|CuI cells with good reproducibility. The fill factor (FF) and power conversion efficiency (η) were about 47.8% and 2.8%, respectively.

Effect of film thickness on structural, electrical, and optical properties of Sol-Gel deposited layer-by-layer ZnO nanoparticles

The structural, electrical, and optical properties of layer-by-layer ZnO nanoparticles deposited using sol-gel spin coating technique were studied and now presented. Thicknesses of the thin films were varied by increasing the number of deposited layers. As part of our characterization process, XRD and FE-SEM were used to characterize the structural properties, current-voltage measurements for the electrical properties, and UV-Vis spectra and photoluminescence spectra for the optical properties of the ZnO thin films. ZnO thin films with thicknesses ranging from 14.2 nm to 62.7 nm were used in this work. Film with thickness of 42.7 nm gave the lowest resistivity among all, 1.39×10 -2 Ω·cm. Photoluminescence spectra showed two peaks which were in the UV emission centered at 380 nm, and visible emission centered at 590 nm. Optical transmittance spectra of the samples indicated that all films were transparent (>88%) in the visible-NIR range. The optical band gap energy was estimated to be 3.21~3.26 eV, with band gap increased with the thin film thickness.

Bandgap Alteration of Transparent Zinc Oxide Thin Film with Mg Dopant

We have successfully demonstrated a bandgap alteration of transparent zinc oxide (ZnO) thin film with Mg dopant by using sol-gel spin coating technique. By increasing the dopant from 0 to 30 atomic percent (at.%), a decrement value in the cutoff is observed, where the absorption edge shifts continuously to the shorter wavelength side, towards 300 nm. This resulted in a significant bandgap increment from 3.28 to 3.57 eV. However, the transmittance of the thin film at 350-800 nm gradually downgraded, from 93 to 80 % which is most probably due to the grain size that becomes bigger, and it also affected the electrical properties. The decrement from 45 to 0.05 mA at +10 V was observed in the I-V characteristics, concluding the significant relationship; where higher optical bandgap materials will exhibit lower conductivity. These findings may be useful in optoelectronics devices.

Variety of Bio-Hydrocarbon Precursors for the Synthesis of Carbon Nanotubes

In this work, we have synthesized carbon nanotubes (CNT) using different bio-hydrocarbon precursors namely palm, olive, coconut, corn and sesame oils. Prior to the synthesis process, thermogravimetric analysis (TGA) characterization was performed on the carbon precursors to facilitate the optimization procedures of CNT and reach maximum yield and higher quality CNT. The CNT arrays were deposited on a silicon substrate by thermal catalytic decomposition of the precursor using 5.33 wt% ferrocene. The synthesis was carried out at 750 °C for 60 min under argon ambient. The samples were characterized using field emission scanning electron microscopy, micro-Raman spectroscopy and TGA analysis. The difference in oil density resulted in different quality and tube diameter of CNT produced. Among all, the CNT synthesized from coconut oil can be considered as the best bio-hydrocarbon precursor for higher quality (ID/IG ~0.62) and good purity (81.95 %) CNT.

The Electrical Characteristics of Aluminium Doped Zinc Oxide Thin Film for Humidity Sensor Applications

The electrical characteristics of aluminum (Al) doped zinc oxide (ZnO) thin film for high sensitivity humidity sensors are presented. The effects of Al doping concentration at 0∼0.6 at % on the Al doped ZnO thin film properties were investigated using current-voltage measurement. The optical and structural properties were characterized using photoluminescence (PL), scanning emission microscope (SEM), and X-ray diffraction (XRD). Parameter 0.6 at % Aluminum doped show high sensitivity and suitable for humidity sensor. PL show an emissions band with two peaks centered at about 380 nm (ultra-violet (UV)) and 600 nm (green) in a room temperature. The length of the nanorods increases as the doping concentration increases. XRD results show the intensity of the (002) peak decreased with the increasing of doping concentration.

Electrical conductivity characteristics of TiO 2 thin film

Titanium Dioxide (TiO2) thin film has been synthesized using sol-gel method and deposited onto glass substrates using spin coating technique. These thin films are then annealed at various temperatures. The electrical and structural characterizations of the as deposited and annealed films were carried out using IV measurement with 4-point probe equipment and scanning electron microscopy (SEM). From this study, it is known that, electrical properties were influenced by changes of annealing temperature. Resistivity of thin films was found to decrease as the annealing temperatures increase. Also indicate in this paper the surface morphology of the thin film.

Electrical characteristics of sol-gel derived aluminum doped zinc oxide thin films at different annealing temperatures

Aluminum (Al) doped zinc oxide (ZnO) thin films with doping concentration of 1 at.% have been prepared using sol-gel spin-coating method. Annealing process has been applied on the prepared thin films at temperatures between 350 and 500 °C. The thin films were characterized using X-ray diffractometer (XRD), UV-Vis-NIR spectrophotometer and current voltage (I–V) measurement system for structural, optical and electrical properties characterization, respectively. XRD pattern reveals the improvement of c-axis orientation with annealing temperatures. The Urbach energy as calculated from transmittance spectra increased with annealing temperatures. I–V measurement results revealed improvement in electrical properties of the thin films with annealing temperatures.

The properties of sprayed nanostructured P-type CuI films for dye-sensitized solar cells application

In our experiments, we provide a new approach for depositing CuI (inorganic compound) thin films using the mister atomizer technique. The CuI solution was sprayed into fine droplets using argon as a carrier gas at different solution concentrations. The solution sprayed was 50ml for all samples with substrate temperature constant at 50°C during the deposition process. The result shows that the CuI thin film properties strongly depend on its precursor concentration. The structural properties were characterized by XRD with strong (111) orientation shows for all the CuI thin films. FESEM images revealed that all the CuI thin films deposited were uniform with the existence of nanostructured CuI particle. The EDX measurement confirms the existence of Cu:I in the films. The nanostructured CuI will improve the penetration of p-type between the mesoporous matrix of TiO2 thin film. Promising conductivity value of about 10° S cm-1 was obtained for CuI thin films deposited by this new deposition method. Low transmittance of below 50% was observed for all CuI thin films. The band gap energy obtained here was between 2.82 eV and 2.92 eV which is much smaller than the reported band gap which is 3.1 eV.

Temperature effects on the production of carbon nanotubes from palm oil by thermal chemical vapor deposition method

In this study we report the effect of various synthesis temperatures of 600 - 1000°C for the synthesis of carbon nanotubes (CNT). Bio-hydrocarbon precursor namely palm oil was utilized as a starting material by thermal vapor deposition method. Ferrocene at 5.33 wt% was directly mixed with palm oil precursor for 30 mins synthesis time. The prepared CNT was collected from the furnace wall and then characterized by field emission scanning electron microscopy, scanning transmission electron microscopy, fourier transform infrared spectroscopy and thermogravimetric analysis. The density, diameter and the purities of the CNT were found to be highly dependent on the temperature changes. The synthesis temperature of 800°C was considered to be the optimum temperature for higher quality and quantity of CNT production.

Preparation of Palm Oil Based Carbon Nanotubes at Various Ferrocene Concentration

In this work, different ferrocene concentration (1.0-8.0 wt%) of bio-hydrocarbon palm oil precursor were utilized to investigate its effect on the characteristics of the produced carbon nanotubes (CNT). The palm oil-ferrocene mixture was vaporized at 450°C and pyrolyzed at 800°C for 30 min time in argon ambient. The CNT were analyzed using field emission scanning electron microscopy, scanning transmission electron microscopy, fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The analysis confirmed different diameter and morphologies of CNT were formed when different ferrocene concentration were used. FTIR spectra show the prominent peak at ~1445, 1736, 2851 and 2925 cm-1 that are identified as CNT and C–Hx respectively.