NASA SBIR 2004 Solicitation


SUBTOPIC TITLE:Energy Conversion for Space Applications
PROPOSAL TITLE:High Efficiency Quantum Dot III-V Thermophotovoltaic Cell for Space Power

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Essential Research, Inc.
6410 Eastland Rd., Suite D
Cleveland ,OH 44142 - 1306
(440) 816 - 9850

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
David V Forbes
6410 Eastland Road, Suite D
Cleveland, OH  44142 -1306
(440) 816 - 9850

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
For NASA deep space science missions, radioisotope thermoelectric generators (RTG) fueled by plutonium-238 are used to provide on-board source of heat, which is then converted to electricity. At present, NASA uses 8% efficient thermoelectric conversion systems. Compound semiconductor thermophotovoltaic (TPV) cells provide an attractive alternative. The highest efficiency TPV cell reported is a 23.6% (radiator at 1039?C, cell at 25?C) InGaAs monolithically interconnected module (MIM) on InP.
We proposed an InGaAs TPV cell which incorporates InAs quantum dots to provide sub-gap absorption thus improving its short-circuit current. This cell could then be integrated into a MIM to achieve a TPV cell whose efficiency would significantly exceed (by about 15% to 20%) the state-of-the-art. In Phase I we demonstrated the feasibility of growing InAs quantum dots on 0.6 eV InGaAs on lattice-mismatched InP, and that these quantum dots, when inserted into the TPV cell, extend the bandedge, providing sub-bandgap absorption.
In Phase II we propose to optimize the quantum dot structures to improve efficiency of the TPV cells, and integrate them into MIMs to achieve very high conversion efficiencies. Resulting higher specific power and power density of the overall power systems will be of great benefit to NASA in the form of lower launch costs and increased mission capability.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Quantum dots will allow NASA not only to improve device efficiency by expanding the spectral response of individual cells, but to improve the temperature coefficients and radiation tolerance as well. The inherently radiation tolerant quantum dots can be used to take advantage of a thermal assist in carrier generation which will actually benefit from higher temperature operation. This is extremely important as NASA attempts to increase array specific power with new concentrator designs and continues to expand the range of environments to be encountered in future missions.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Successful completion of the Phase II work will lead to the development of a very high efficiency TPV cell that will deliver power beyond the realm of any TPV cell that is commercially available, or under development by a commercial supplier. Upon achieving this goal, Essential Research Incorporated plans to enter into licensing arrangement with Emcore Photovoltaic, to manufacture and market this product, while working with them for a successful technology transfer and continuing R&D work. Such an arrangement will make this cell available not only to NASA, but also to commercial satellite manufacturers.

Form Printed on 08-01-05 13:52