Material and device considerations for cascade solar cells

The cascade solar cell using two or more junctions has the potential for significantly increasing the efficiency of solar cells beyond that of single-junction cells. Theoretical calculations give AM0, one sun efficiencies of 30 percent or slightly higher. Before these efficiencies can be achieved, many material and device problems must be solved. This paper discusses these major material and device problems as related to the cascade solar cell concept. Also presented are some experimental results on materials and devices which are presently being explored for use in the cascade solar cell.