Pyrocatechol violet sensitized Ho-TiO₂/ZnO nanostructured material: As photoanode for dye sensitized solar cells

In this work TiO₂, Holmium doped (Ho-TiO₂) Titanium oxide nanoparticles (NPs) and the corresponding nanostructured combinations (Ho-TiO₂/ZnO NC) were successfully synthesized through sol gel method and reflux techniques respectively. The prepared nano materials were characterized with the help of x-ray diffraction Analysis (XRD), UV-visible spectroscopy, Scanning Electron Microscopy (SEM), Energy dispersive x-ray Analysis (EDX) and Fourier Transform infrared spectroscopy (FT-IR). The absorption spectra of nano materials were used for band gaps calculation. The band gap of pure TiO₂ NPs was found to be 3.10 eV which was effectively tuned to 2.65 eV by the doping of Holmium at different concentrations. XRD patterns confirmed the crystalline nature and purity of the synthesized nano materials. Morphology and elemental composition of the material were investigated using SEM and EDX respectively. FTIR helped in detecting the functional groups and grafting of the dye on the surface of nanoparticles. The nano materials were used as Photo-anodes in dye sensitized solar cells (DSSC). Pyrocatechol Violet dye was used as a photo-sensitizer. P3HT (polymer), a hole conducting polymer, was employed as a solid state electrolyte. I-V measurements were used for characterization of fabricated solar cells. Ho-TiO₂/ZnO nanomaterial photosensitized with Pyrocatechol violet dye gave the highest percentage efficiency of 1.51. Other characteristic parameters of the fabricated devices such as short circuit current (Jsc), open circuit voltage (Voc), maximum power point (Mpp) and fill factor were found to be 11.2 mA cm^-2, 0.41 V, 1.55(mW cm^-2) and 0.33 respectively.