29.5-PERCENT-EFFICIENT GALNP GAAS TANDEM SOLAR-CELLS/

We report on multijunction GaInP/GaAs photovoltaic cells with efficien cies of 29.5% at 1-sun concentration and air mass (AM) 1.5 global and 25.7% 1-sun, AM0. These values represent the highest efficiencies achi eved by any solar cell under these illumination conditions. Three key areas in this technology are identified and discussed; the grid design , front surface passivation of the top cell, and bottom surface passiv ation of both cells. Aspects of cell design related to its operation u nder concentration are also discussed.