Investigations on anodic photocurrent loss processes in dye sensitized solar cells: comparison between nanocrystalline SnO2 and TiO2 films

Anodic photocurrent loss processes have been investigated for dye sensitized nanocrystalline SnO2 and TiO2 solar cells by means of electrical bias dependent photocurrent spectroscopy. Electron injection efficiency is not dependent on visible excitation wavelengths under electrical bias application for both films. Under an identical cell configuration, the unsensitised SnO2 film exhibited cathodic photocurrent generation while no cathodic photocurrent was detected for the TiO2 film. The origins of these observations are discussed. The experimental results suggest that the electron transfer reaction from the SnO2 to the electrolyte must be accelerated at the SnO2 surface by the bias application.