Optoelectronics of solution processed core shell zinc oxide nanowire/zinc sulphide heterostructure for dye sensitized solar cell applications

• Developed a low cost, solution-based deposition process for synthesis of ZnO/ZnS heterojunction material.
• When compared with pristine ZnO nanowire, the ZnS coating effectively absorbs the incoming photons.
• Optimized ZnS coating can improve ZnO-based dye sensitized solar cells by protecting the ZnO surface from the acidic dye.
• Excessive ZnS coating on the ZnO nanowires reduces the dye sensitized solar cell’s performances due to reduced surface area.

ZnS/ZnO nanowire core–shell heterostructures were prepared by a solution-based process using a combination of hydrothermal growth synthesis and chemical bath deposition (CBD). The fabricated heterojunctions were extensively characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and photoluminescence emission measurements. It was found that the CBD process provides a conformal ZnS coating onto the ZnO nanowire surfaces that enhances light absorption. As a demonstration, dye sensitized solar cells (DSSCs) were fabricated with ZnS coated and pristine ZnO nanowire as photoanodes. It was found that ZnS thickness strongly influences the performances of the DSSCs and that there is an optimum thickness for the ZnS coating.

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