Abstract: Photoelectrochemical cell structures and methods of fabrication are disclosed which provide for easily manufactured efficient energy conversion devices. The structures incorporate one or more chambers for the electrolyte, and utilize semiconductor photoelectrodes. In the plural chamber structure, the semiconductor may be opaque, and need not necessarily be a thin film. Specific dopants for the semiconductor provide for decreased dark current and increased open circuit voltage. Post deposition treatment is disclosed for the semiconductor to provide an increased shorting current. Increased sputtering wattage is provided to increase the short circuit current available from the cell. An electrolyte composition is described having improved performance at high light intensity.