Study of Dye-Sensitized Solar Cells by Scanning Electron Micrograph Observation and Thickness Optimization of Porous TiO2 Electrodes

In order to improve the photoenergy conversion efficiency of dye-sensitized solar cells (DSCs), it is important to optimize their porous electrodes. This paper examines the surface and cross-sectional views of the electrodes using scanning electron micrography. Two types of samples for cross-sectional viewing were prepared by mechanically breaking the substrate and by using an Ar-ion etching beam. The former displays the surface of the particles and the latter shows the cross-section of the particles. We found interesting surface and cross-sectional structures in the scattering layer containing the 400 nm diameter particles, which have an angular and horned shape. The influence of particle size and the thickness of the nanocrystalline- electrode in DSCs using four kinds of sensitizing dyes (D149, K19, N719 and Z907) and two kinds of electrolytes (acetonitrile-based and ionic-liquid electrolytes) are discussed in regards to conversion efficiency, which this paper aims to optimize.