In recent years there has been an increasing interest in syscems which enable the conversion of solar energy into electri calor chemical energy. Many types of systems have been proposed and studied experimenta11y, the fundamentals of which extend from solid state physics to photo- and electrochemistry. For most of the systems considered excitation of an electron by absorption of a photon is fo1lowed by charge separation at an interface. It follows that the different fields involved (photovo1taics, photo electrochemistry, photogalvanics, etc.) have several essential aspects in common. It was...