SBIR-STTR Award

Quantum dots are nanoscale materials that have already improved the performance of optical sensors, lasers, and light emitting diodes. The unique properties of these nanomaterials offer tremendous benefit in developing high-efficiency photovoltaic solar cells as well. Theoretical studies predict a potential efficiency of 63.2 %, for an array of quantum dots sandwiched between the p and n-type layers in a typical photovoltaic junction. This would yield an increase in efficiency of a factor of 2 over any state-of-the-art (SOA) devices available today. We are proposing to utilize quantum dots to develop a super high-efficiency multijunction III-V solar cell for space. In metamorphic triple junction space solar cells, pioneered by Essential Research, Inc., the InGaAs junction or bottom cell of the three-cell stack is the current limiting entity. We propose an InGaAs cell which incorporates InAs quantum dots to provide sub-gap absorption and thus improve the short-circuit current. This cell could then be integrated into a conventional three-cell stack to achieve a space solar cell whose efficiency would dramatically exceed current SOA standards. A theoretical estimate predicts that a InGaAlP(1.95 eV)/InGaAsP(1.35 eV)/InGaAs(1.2 eV) triple junction cell incorporating quantum dots to improve the bottom cell current would have an efficiency exceeding 40%.

Potential NASA Commercial Applications:
(LIMIT 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 150 WORDS) Successful completion of Phase I and Phase II of the proposed work will lead to the development of a radiation-resistant solar cell that will deliver power beyond the realm of any solar 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 on the product.

We are proposing to utilize quantum dots to develop a super high-efficiency multijunction III-V solar cell for space. In metamorphic triple junction space solar cells, pioneered by Essential Research, Inc., the InGaAs junction or bottom cell of the three-cell stack is the current limiting entity. In Phase I of this program, we demonstrated that InAs quantum dots can be formed by MOVPE, and then incorporated in an InGaAs cell to provide sub-gap absorption and thus improve its short-circuit current. For the Phase II work, we propose to optimize this quantum dot InGaAs cell, and develop a three-cell stack to achieve a space solar cell whose efficiency would dramatically exceed current SOA standards. A theoretical estimate predicts that a InGaAlP(1.95 eV)/InGaAsP(1.35 eV)/InGaAs(1.2 eV) triple junction cell incorporating quantum dots to improve the bottom cell current would have an efficiency exceeding 40%.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. 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 NASA Commercial Applications:
(LIMIT 100 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 100 WORDS) Successful completion of the Phase II work will lead to the development of a very high efficiency solar cell that will deliver power beyond the realm of any solar 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. A letter of support and endorsement from Emcore is attached.