Production of Useful Znse Nano-Film Electrodes By Electrodeposition Onto Conducting Glass and Plastic Substrates

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غنام, هبه مهند محمد
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An-Najah National University
ZnSe thin film electrodes have been deposited on two types of transparent conducting substrates, fluorine doped tin oxide (FTO) coated glass and indium doped tin oxide (ITO) coated plastic sheets, by electrochemical deposition (ECD). The prepared thin films have then been characterized by various techniques (X-ray diffraction (XRD), scanning electron microscopy (SEM) and electronic absorption spectra). Effects of deposition time, annealing temperature (100 °C and 150 °C under an inert gas), cooling rate (quickly and slowly cooled) and modification with MWCNTs film PEC characteristics, have been investigated. The ZnSe thin films have p-type conductivity as confirmed by PEC measurements. XRD measurements show that ZnSe/FTO/glass thin films exist in mixed hexagonal and cubic phases, while the ZnSe/ITO/plastic has hexagonal phase only. The electronic absorption spectra for the films deposited on FTO/glass showed band gap values between (2.4-2.6 eV), while for films deposited on ITO/plastic, the band gap values are between (2.82-3.05eV). The band gap value decreases with higher annealing temperatures. Rapidly cooled films show higher band gap than slowly cooled ones. The films deposited on FTO/glass give higher conversion efficiency (0.84%) than the films deposited on ITO/plastic (0.087%). Annealing the ZnSe thin films lowered their PEC characteristics. Effect of using multiwalled carbon nanotube (MWCNT) layers onto ZnSe/FTO/Glass electrodes has been investigated. The MWCNT layer has been introduced by two different methods: by insertion between the ZnSe and the FTO layers (ZnSe/MWCNT/FTO/Glass), or by coating the ZnSe with MWCNT (MWCNT/ZnSe/FTO/Glass). The ZnSe/MWCNT/FTO/glass shows higher conversion efficiency (1.68%) compared to (0.84%) for ZnSe/FTO/Glass electrode. In this case, the MWCNT layer behaves as a charge transfer agent between the ZnSe layer and FTO substrate. The MWCNT/ZnSe/FTO/glass electrode exhibits lower conversion efficiency (0.61%). This is possibly due to the ability of MWCNT coating to block the incident light from reaching the surface of ZnSe.