Application of TiO 2 nano-particles on the electrode of dye-sensitized solar cells

Abstract

In this study, nano-TiO 2 thin film electrode and solar cell have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible absorption spectra, contact angle, X-ray photoelectron spectroscopy (XPS), and current–voltage characteristics analyses. X-ray diffraction patterns show that the best sintering temperature of a nano-TiO 2 film is 600 °C, at which TiO 2 anatase phase forms best and the particle size of 8–10 nm can be obtained. The SEM images of a nano-TiO 2 thin film show that the surface of the film is smooth and porous, and the thickness of the nano-TiO 2 film is 4 μm. The measurements of contact angle between nano-TiO 2 film and deionized water (DI water) reveal that the nano-TiO 2 film is super-hydrophilic when solarized under ultraviolet. The electrode of dye-sensitized solar cell is used as a free-base porphyrin with carboxyl group, 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) as the sensitizer to adsorb onto the TiO 2 thin film. From the results of ultraviolet–visible absorption spectra and XPS analyses of the electrode, the effects of nano-TiO 2 particles’ addition to the electrode of dye-sensitized solar cell can improve the absorption of visible light (400–700 nm) and increase electrons transferred from TCPP to the conduction band of TiO 2, resulting in the enhancement of efficiency for dye-sensitized solar cells.