Dye-sensitized solar cells fabricated using ZnO:Cu thin films and dye extracted from Hypericum perforatum L. flowers

Dye-sensitized solar cells (DSSC) were designed utilizing pure and copper-doped zinc oxide (ZnO:Cu) nanoparticles and the dye extracted from dried Hypericum perforatum L. (H. perforatum) flowers. The ZnO:Cu thin films were grown using the successive ionic layer adsorption and reaction (SILAR) method on tin-doped indium oxide-coated (ITO) glass substrates at 85 °C. Regarding the molar ratio of Cu ions to Zn ions, Cu had a doping concentration of 0.5%, 1%, and 2%. The crystalline nature, morphological, compositional, and optical properties of the synthesized ZnO:Cu thin films were studied using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), energy dispersive x-ray spectrometry (EDS), UV-vis spectroscopy, and Fourier transformation infrared (FTIR) spectroscopy. The SEM results indicated the formation of a porous structure on the surface of ZnO:Cu thin films, which provided more active sites for dye molecules and electrolyte ions. A DSSC, produced by using a pure ZnO thin film, showed a current density (Jsc) of 7.66 mA/cm2 with an open-circuit voltage (Voc) of 0.98 V and an overall efficiency (η) of 2.47%