Abstract: Schottky and p-n type photo-electrochemical cells are disclosed. These cells are suitable for sunlight and use gelled electrolytes based either on aqueous or solvent substances. The gel is a light-transparent, inert substance. These cells have at least one electrode of a semiconductor. The second electrode may be a metal or a semiconductor of the opposite conductivity type. These gelled electrolyte cells display performance advantages over their corresponding liquid electrolyte cell structures. Higher photovoltages and photocurrents are obtained along with a reduction in the rate of undesired photo-decomposition of one of the electrodes. Furthermore, gelled electrolytes may be contained between two closely spaced electrodes. This type of cell reduces both ohmic losses and light attenuation.