Cyclic voltammetry analysis of transition metal chalcogenide tungsten ditelluride (WTe₂) thin films

Fan, Kerry (2018) Cyclic voltammetry analysis of transition metal chalcogenide tungsten ditelluride (WTe₂) thin films. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

The development of thin films technology for solar panel application is rising due to the effort of researchers to find an alternative to replace expensive silicon wafer and to improve the efficiency of solar panel. Transition metal chalcogenide (TMCs) are semiconductor that has unique properties from having ideal bandgap between 1.0 to 2.0eV. This characteristic of TMCs becomes the interest of researchers to develop an efficient photovoltaic material using transition metal chalcogenide thin films. Tungsten ditelluride (WTe2) is one of the TMCs that can be applied as thin film technology for solar panel application. The purpose of this research is to synthesize the stoichiometry WTe2 thin films by electrodeposition method, to determine the deposition parameters such as deposition potential and deposition time for the growth of thin films via cyclic voltammetry analysis, and to characterize the composition and crystallography using X-Ray Diffraction (XRD) and surface morphological properties of WTe2 thin films by using Scanning Electron Microscopy (SEM). The suitable potential for the deposition of WTe2 had been determined by using cyclic voltammetry. Three precursors solutions without additive and with additive, EDTA and TEA was studied. It is found that EDTA is suitable to be used for the deposition of WTe2 thin films to improve the adhesion of thin films on ITO glass substrates. The range of potential suitable for the deposition is -0.85V to -1.35V. Electrodeposition method is used to deposit WTe2 thin films. The thickness of WTe2 thin films are calculated by using gravimetric weight difference method where -0.95V is found to be the most suitable deposition potential in giving a dark uniform black film. From XRD, the presence of WTe2 thin films are confirmed with the presence of sharp peak indicating polycrystalline structure. Surface morphological study by SEM shows that 20 minutes deposition time gives uniform WTe2 thin films formation with uniform film distribution. From the results obtained, WTe2 thin films is successfully deposited on ITO glass substrates under the optimum condition of deposition potential -0.95V for duration of 20 minutes deposition time with the presence of EDTA and electrolyte precursors composition of 0.0038M TeO2 + 0.0024M H2WO4 + 0.021M EDTA.

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