Hybrid Structure of TiO<sub>2</sub> Nanofiber and Nanoparticle for Dye-Sensitized Solar Cells

Abstract

Hybrid structure of TiO2 nanofiber and nanoparticle as a photoelectrode was very attractive in dye-sensitized solar cells (DSCs) because TiO2 nanoparticle provided a high specific surface area to adsorb the N719 dye and TiO2 nanofiber was a direct path to transfer photoelectron from dye to electrode. TiO2 nanofiber film was prepared with titanium-tetraisopropoxide (TTIP) and polyvinylpyrrolidone (PVP) based precursor by electro-spinning process. To fabricate the hybrid structure, TiO2 nanoparticular paste was screen printed on the TiO2 nanofiber film. Electrospun TiO2 nanofiber film and screen printed TiO2 nanoparticular film were combined in layer by layer method. These films were observed as an anatase phase by X-ray diffraction pattern. Thickness and diameter of TiO2 nanofibers were ~5μm and ~400nm, respectively. Thickness and particle size of TiO2 particles were ~5μm and ~20nm, respectively. Compared to conventional DSCs, higher short circuit current densities (Jsc) of 6.47 mA/cm2 and higher power conversion efficiency of 3.06 % were measured in DSCs having hybrid structure of TiO2 nanofiber and nanoparticle. Electrochemical impedance spectroscopy (EIS) was observed to understand an electron transfer and life time.