Photoconversion of Dye-Sensitized Solar Cells with a 3D-Structured Photoelectrode Consisting of Both TiO2 Nanofibers and Nanoparticles

Abstract

In dye-sensitized solar cells, a three-dimensional (3-D)-structured photoelectrode of TiO2 nanofibers and nanoparticles was successfully fabricated by electro-spinning and screen-printing processes. Structures with one-dimensional nanofibers can be expected to improve the charge transport in a photoelectrode. The microstructure and crystalline structure were observed by field-emission scanning electron microscopy and with an x-ray diffractometer, respectively. The particle size of the TiO2 particles and the diameters of the TiO2 nanofiber in the 3-D-structured photoelectrode were ~30 nm and ~500 nm, respectively. The total thickness of the TiO2 layer in the 3-D-structured photoelectrode, which is composed of a nanoparticle layer of ~12 μm and a nanofiber layer of ~8 μm, was ~20 μm. The crystalline, anatase phase was also determined. In these dye-sensitized solar cells with a 3-D-structured layer, a short-circuit current density of 12.36 mA/cm2, an open-circuit voltage of 0.74 V, a fill factor of 0.46, and an energy conversion efficiency of 4.18% were observed. These values are higher than those of dye-sensitized solar cells with a conventional TiO2 nanoparticle layer. The proposed 3-D-structured photoelectrode consisting of TiO2 nanofibers and nanoparticles can help improve the performance of commercial dye-sensitized solar cells.