SURFACES FOR PHOTOELECTROCHEMICAL CELLS

The fundamental considerations which determine semiconductor surface barriers and electrolyte energy levels in PEC cells arc discussed. It is shown that redox levels, barrier heights and dissolution reactions are related and depend on the nature of all components, including counter electrode and solvent electrolyte, in any particular system. The efficiency is shown to be subject to the Carnot limitation, as for heat engines, by regarding the illumination as producing a hot electron distribution. A large area (∼0.3 m2) system based on conducting TiO2 films has been found stable against several months of operation and deliberate hard usage. It is concluded that the scope for combining different components for optimising PEC cells as economic solar converters is considerable. © 1979.