(photovoltaic cell). A battery-like device in which the radiant energy of the sun is converted to electrical energy by means of a semiconductor. The essential component of a solar cell is a thin sheet or wafer of crystalline or amorphous silicon, plus doping agents. The crystalline form is used in 3-inch squares, but the hydrogenated amorphous form is effective in 1-foot squares which are produced as vapor-deposited coatings on glass only a few microns in thickness. A notable advance in the technology of solar cells is the experimental development of a photoelectrochemical cell, that utilizes silicon electrodes by which incident light is converted to energy. The conversion efficiency is sufficient to indicate that this type of cell may have an important future. Its success is due to microthin films of doped oxides of alumina or magnesia deposited on the electrode surfaces, which in turn are coated with platinum a few angstroms thick. The cell can also be operated as a battery for use in remote power sources.
