It seems that ferric oxide is advantageous as a semiconductor photoelectrode for utilizing solar energy (1–10). Ferric oxide is an n-type semiconductor, its bandgap is reasonable for such purposes, it can be manufactured easily and cheaply, and it is reasonably stable. It does, however, suffer from the disadvantage of low quantum efficiency. The efficiency can be increased if the surface processes are understood, and it is known how to suppress surface recombination. Recently, analysis of phototransients was used by Iwanski et al. to investigate processes taking place on illuminated ferric oxide electrodes (8). The results of similar experiments are presented here. Our aim was to determine whether hole injection at the interface proceeds directly from the valence band or via surface states. With this in mind, the photocurrent was measured on ferric oxide electrodes at constant electrode potential and slightly modulated illumination as a function of reducing agent concentration. The average value of the photocurrent was measured directly, and the current transients due to light modulation were recorded, using the signal averaging technique.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
- Materials Chemistry
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films