A GaAs/GalnP dual junction solar cell grown by molecular beam epitaxy

We report the recent result of GaAs/GalnP dual-junction solar cells grown by all solid-state molecularbeam-epitaxy （MBE）. The device structure consists of a GaIn0.4sP homojunction grown epitaxially upon a GaAs homojunction, with an interconnected GaAs tunnel junction. A photovoltaic conversion efficiency of 27% under the AM1.5 globe light intensity is realized for a GaAs/GaInP dual-junction solar cell, while the efficiencies of 26% and 16.6% are reached for a GaAs bottom cell and a GaInP top cell, respectively. The energy loss mechanism of our GaAs/GalnP tandem dual-junction solar cells is discussed. It is demonstrated that the MBE-grown phosphide-containing Ⅲ-V compound semiconductor solar cell is very promising for achieving high energy conversion efficiency.