Nordin Sabli

CuZnSnSe Thin Film Electrodes Prepared by Vacuum Evaporation: Enhancement of Surface Morphology and Photoelectrochemical Characteristics by Argon Gas

CuZnSnSe thin films were deposited by thermal vacuum evaporation with and without argon gas stream at room temperature. Effect of argon gas on surface morphology and on photoelectrochemical (PEC) characteristics of the films was studied. The electrodes prepared under argon gas showed better enhanced characteristics, due to slower nucleation and growth due to dilution effect of the inert gas. While both electrodes showed soundly good PEC behaviors in a hexacyanoferrate(III)/hexacyanoferrate(II) redox couple, the electrode with argon gas showed 20 fold enhancement in photoactivity, compared to the one without argon gas. The results manifested thin film electrode performance can be enhanced simply by inclusion of argon inert gas inside the preparation chamber, with no need for other procedures such as annealing.

Determination of ethanol concentration of ethanol/water mixture solutions with open ended coaxial method

This study presents a simple and non-destructive procedure to determine ethanol concentration of ethanol/water solution at ambient temperature based on HP85070B open ended coaxial dielectric constant measurement. The motivation for this study stems from the fact that the ‘true’ concentration of ethanol in a ‘labeled’ container could be ‘spoiled’ due to hygroscopic nature of ethanol, evaporation and other factors. The dielectric constant measurements of eight samples with different molar fraction were validated with modified Cole-Cole-Debye (3CC) simulations. A 5th degree polynomial calibration equation was developed based on 3CC simulations with R2 = 0.9998 and used to estimate the ‘true’ concentration of three ethanol samples obtained from ‘labeled’ containers kept in laboratory. The ethanol concentrations of two of the samples were found to be much lower than what was indicated on their labels, hence, assumed spoiled.

Effect of argon gas flow rate on properties of film electrodes prepared by thermal vacuum evaporation from synthesized Cu2SnSe3 source

This work describes a new technique to enhance photoresponse of metal chalcogenide-based semiconductor film electrodes deposited by thermal vacuum evaporation under argon gas flow from synthesized Cu2SnSe3 sources. SnSe formation with Cu-doped was obtained under higher argon gas flow rate (VA = 25 cm3/min). Higher value of photoresponse was observed for films deposited under VA = 25 cm3/min which was 9.1%. This finding indicates that Cu atoms inside the SnSe film were important to increase carrier concentrations that promote higher photoresponse.

Effect of High Intensity Light Irradiance on CuInSe2 Thin Films

CuInSe2 has been a good candidate for photovoltaic material due to its direct band gap and high absorption coefficient. As the stability of photovoltaic are generally dependent on the aggressive environment, i.e. sun light, the CuInSe2 thin film can degrade after long exposure of high intensity light irradiance. The present study reports on the effect of high intensity light irradiance to the electrical and optical properties of thermal evaporated CuInSe2 thin films. The thin films were exposed to light intensity of 250 W/m2, 500 W/m2, 750 W/m2, 1000 W/m2 and 1500 W/m2 using halogen lamp. We noticed an increasing trend in resistivity after light exposure at all intensities due to the increase of light-induced defects in the films which act as recombination centre for electron-hole pair. Crystallinity of CuInSe2 thin films decreases with increasing intensity of light exposure as a result of light-induce defect. CuInSe2 thin films are found to have higher optical band gap compared to reported 1.01eV due to the amorphous structure of the film and relatively higher surface roughness.