Photovoltaic AlGaAs/GaAs Solar Cells
This project focuses on the optimization of single junction solar cells in the AlGaAs/GaAs material system. GaAs has a band gap of 1.4 eV and is nearly ideal for optimizing the single junction solar cell efficiency. A single junction GaAs solar cell has so far demonstrated an efficiency of 24.7 % at 1 sun, and this efficiency can be improved by going at higher sun illumination. The ideal single junction GaAs solar cell efficiency at 1 sun is 31 %. We have designed and fabricated single junction GaAs solar cells with the goal of maximizing the back surface field. These devices will be shortly characterized. We expect that quantum wells and quantum dot solar cells will have higher efficiencies. Intermediate band solar cells might be another way to increase the efficiency of solar cells. A recent work on GaAs solar cells has reported a record efficiency of 28.2 % using photon recycling and high quality material to minimize non-radiative recombination. This approach relies on having a layer in the solar cell to reflect the photons with good efficiency.
This project will study different approaches for realizing high efficiency solar cells. The University of Maryland has established a close collaboration with the Army Research Lab in Adelphi.