Improvements in silicon solar cell efficiency

Four significant results are described relating to improved solar cell efficiency. These are: (1) the demonstration of cells with efficiencies in excess of 20 percent under terrestrial test conditions (Am1.5, 100 mW/sq cm, 28 C); (2) the demonstration of cells with greater than 18 percent efficiency under space radiation (AM0, 25 C); (3) the development of a very practical sequence not requiring photolithography, vacuum evaporations, or double layer antireflection coatings which produces similarly high efficiencies; and (4) the demonstration of 18 percent efficiency with this approach upon solar grade Czochralski substrates of both small and large area.