Improved efficiency of GaSb solar cells using an Al0.50Ga0.50As0.04Sb0.96 window layer

The increasing number of subcells in multi-junction structures imposes the use of narrow bandgaps for a full harvesting of the solar spectrum. In this context, gallium antimonide (GaSb) and its lattice-matched alloys offer a great potential. To date, GaSb-based multi junction solar cells exhibit experimental results below theoretical expectations, due to a limiting GaSb subcell. In this paper, a new design of GaSb cells comprising an Al0.50Ga0.50As0.04Sb0.96 window layer is studied. With this design, an excellent conversion efficiency of 7.2% is achieved under 1 sun (AM1.5G) illumination. This performance is attributed to a significant improvement in short-circuit current.