Advanced Epitaxial Lift-Off Quantum Dot Photovoltaic Devices

We propose to develop a high-efficiency, triple-junction, epitaxial lift-off (ELO) solar cell by incorporating quantum dots (QDs) within the current-limiting subcell. We intend to leverage existing QD epitaxy processes developed by the Rochester Institute of Technology and combine this with MicroLink's expertise in multi-junction cell growth and ELO technology. We will employ QDs to enhance the middle cell absorption in a InGaP/GaAs/InGaAs metamorphic IMM cell. Detailed balance calculations indicate that the triple junction efficiency can be increased to ~42% by reducing the bandgap of the middle cell to ~1.2 eV. The combination of the QD technology with multi-junction ELO technology will be exploited in two ways: i) ELO GaAs cells with QD can be grown into full triple-junction cells and ii) back-surface reflectors on the ELO cells will be used to improve absorption by routing IR light for a second pass through the QD subcell. The relevance of this work to NASA is that it will result in lightweight, high-efficiency, triple-junction solar cells that will have a specific power > 500 W/kg. In addition, the use of QDs has been shown to improve radiation tolerance of the photovoltaic device.

When fully developed, the quantum dot solar cells will be suitable for use in the following NASA applications: replacement for conventional triple junction cells on spacecraft, solar panels for next generation solar electric propulsion (SEP) spacecraft, and solar-powered high altitude, long endurance (HALE) aircraft.

The lightweight, high efficiency solar cells to be developed in this program can be used in the following non-NASA applications: replacement for conventional triple junction cells on spacecraft, solar-powered high altitude, long endurance (HALE) aircraft, solar blankets for terrestrial power generation, and terrestrial solar concentrators.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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