Description: MicroLink proposes to develop a phosphide-based ELO-IMM four-junction (4J) solar cell that will enhance the performance and capabilities of solar photovoltaic arrays for a variety of future NASA missions. Relative to state-of-the-art incumbent GaInP/GaInAs/Ge 3J space solar cells, the proposed phosphide-based 4J solar cell has superior radiation tolerance, higher beginning-of-life (BOL) and end-of-life (EOL) efficiencies, lower areal mass density, higher specific power, and lower cost. The improved radiation tolerance is enabled by eliminating arsenide-based subcells in favor of only phosphide-based subcells. A reduction in the mass of the solar cell relative to incumbent technology is enabled by removal of the thick GaAs substrate. Cost savings compared to incumbent technology are enabled by the recovery and reuse of the substrate via the ELO process. The superior radiation tolerance can also relax the requirements for radiation shielding, enabling further reductions in array mass and stowed volume.

Benefits: The proposed phosphide-based 4J solar cells are ideally suited for high efficiency multi-junction solar cell arrays for NASA applications requiring superior radiation tolerance, higher BOL and EOL efficiencies, lower areal mass density, higher specific power, or lower cost relative to incumbent Ge-based 3J space solar cells. Potential applications include solar electric propulsion programs and missions involving extreme radiation environments. Arrays based on the proposed solar cells will be suitable for NASA missions ranging from near-Earth to deep space. Lockheed Martin, Space Systems Loral, and Boeing have shown great interest in MicroLink?s work and in future applications of low mass, flexible photovoltaic module technologies that can support NASA's SEP program as a replacement for the solar cells in existing spacecraft.

Manufacturers of commercial satellites and unmanned aerial vehicles (UAVs) are interested in MicroLink's low mass and power dense ELO solar cell technology for the potential to reduce costs while improving the efficiency compared to commercially available Ge-based cells. Attractive military and civilian applications include the ability to recharge batteries in remote locations.