title: Multijunction solar cells for conversion of concentrated sunlight to electricity.
abstract: Solar-cell efficiencies have exceeded 40% in recent years. The keys to achieving these high efficiencies include: 1) use of multiple materials that span the solar spectrum, 2) growth of these materials with near-perfect quality by using epitaxial growth on single-crystal substrates, and 3) use of concentration. Growth of near-perfect semiconductor materials is possible when the lattice constants of the materials are matched or nearly matched to that of a single-crystal substrate. Multiple material combinations have now demonstrated efficiencies exceeding 40%, motivating incorporation of these cells into concentrator systems for electricity generation. The use of concentration confers several key advantages.
authors.affiliation: National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA. sarah.kurtz@nrel.gov
authors.forename: Sarah
authors.initials: S
authors.lastname: Kurtz
authors.forename: John
authors.initials: J
authors.lastname: Geisz