Zinc oxide nanostructure-based dye-sensitized solar cells

Developing new technologies that could lead to alternatives to the traditional silicon-based solar panels, and to efficiently light the world in the future, is critically important because of limited natural petroleum resources. Dye-sensitized solar cells (DSSCs) are promisingly efficient and clean hybrid, organic–inorganic, low-cost molecular solar cell devices. The key components of DSSCs are the organic dyes that play the role of a photosensitizer—like the chlorophyll of a green plant that is responsible for photosynthesis—and nanostructured semiconductor metal oxides. Because of their unique, multifunctional properties, zinc oxide (ZnO) nanostructures are promising materials to use to create photoanodes for DSSCs. This review looks at recent developments in the field of ZnO-based DSSC devices; synthesis of ZnO nanostructures with variable morphologies, including nanorods, nanofibers, nanotubes, nano-/microflowers, thin sheets, and nanoaggregates; factors that control the growth and morphologies of these nanomaterials; and the role of crystallographic planes for the synthesis of versatile ZnO nanostructures. This review also covers photoelectrode fabrication, DSSC device components, nature and chemical features of the dyes used as photosensitizers, and operational principles. In addition, various photovoltaic parameters such as current density, open-circuit voltage, fill factor, photoconversion efficiency, and factors that influence these parameters for ZnO-based DSSCs are summarized and discussed.