CuO FILMS PREPARED BY COMBINED ELECTROCHEMICAL AND CHEMICAL BATH DEPOSITIONS
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Date
2022-06-16
Authors
Sondos Waleed "Mohammad Ali" Omareyyeh
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Abstract
Abstract
Background: Thin film electrodes are emerging in solar energy technology to produce electricity from light. CuO is one example of common semiconductors that did not yield high photoelectrochemical (PEC) performance. This is a problem to solve.
Objectives: The present study aims at producing CuO thin film electrodes with high PEC performance. CuO thin films will be deposited onto FTO/glass substrate by electro-chemical deposition (ECD), chemical bath deposition (CBD) and combined EC/CB deposition techniques. The resulting electrodes will be assessed in photoelectrochemical process, after being modified by annealing and by cooling rate control (fast and slow cooling).
Methodology: Three techniques have been used to deposit CuO thin film on fluorine doped tin oxide (FTO) Glass substrate. These techniques are; chemical-bath deposition (CBD), electrochemical deposition (ECD) and combined electrochemical and chemical bath (ECD/CBD) deposition technique. The prepared films were characterized by various methods including; X-ray diffraction (XRD), scanning-electron microscope (SEM), electronic absorption spectra and photoelectrochemical measurements. Effect of annealing temperature, cooling rate and deposition time have also been studied. The CuO films exhibit p-type conductivity as shown by photoelectrochemical characteristics (PEC) study.
Results: The prepared films exhibit low photoelectrochemical behaviors. Higher PEC characteristics were gotten from CBD method, but they need annealing at temperatures higher than 150 ̊C in order to remove the resulting Cu(OH)2. Annealing at high temperatures affect CuO films negatively, since CuO has a very small band gap (1.3-2.1 eV). Combined ECD/CBD technique does not improve CuO thin film characteristics which against our predictions. The prepared films show good stability measurements.
Conclusions: The prepared films exhibit low photoelectrochemical behaviors. CBD method is the best method to prepare CuO films with higher PEC characteristics, but needs annealing to remove resulting Cu(OH)2. Because the CuO has very small band gap, it is sensitive to annealing at high temperature. Higher temperatures affect the films negatively. On the other hand, ECD method gives CuO films with more uniform structures with no Cu(OH)2 product, but do not have improved PEC characteristics. Films deposited by combined ECD/CBD did not show improved PEC characteristics. Annealing ECD/CBD films negatively affects their SEM micrographs, due to sensitivity of the ECD layer to annealing.
Suggestions: CuO thin films can be prepared with more modifications, e.g: coating with multiwalled carbon nano tubes (MWCNT) is recommended. More annealing temperatures should be studied to optimize film characteristics. Electrochemical deposition may be repeated several times to enhance film performance. Doping the prepared CuO films with other dopants is recommended. Depositing combined EC/CB CuO thin film on other type of substrates. For example, Indium tin oxide (ITO) substrate.
Keywords: Thin films, chemical bath deposition (CBD), electrochemical deposition (ECD), combined EC/CB deposition, annealing.