NASA SBIR 2007 Solicitation

FORM B - PROPOSAL SUMMARY


PROPOSAL NUMBER: 07-1 S3.03-9293
SUBTOPIC TITLE: Power Generation and Storage
PROPOSAL TITLE: High Efficiency, High Mass Specific Power Two-Terminal Solar Cells

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
EPIR Technologies, Inc.
590 Territorial Drive, Suite B
Bolingbrook, IL 60440 - 4634
(630) 771-0203

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Paul Boieriu
pboieriu@epir.com
590 Territorial Drive, Suite B
Bolingbrook, IL 60440 - 4634
(630) 771-0203

Expected Technology Readiness Level (TRL) upon completion of contract: 3 to 4

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
Future NASA missions will require significant improvements in photovoltaic energy conversion efficiency (>30%) and mass specific power (>600 W/kg), and improved radiation tolerance. We propose to develop a high efficiency monolithic three-junction, two-terminal solar cell using lattice matched HgCdZnTe and/or HgCdMgTe alloys, which will offer great advantages in terms of weight and interconnect simplicity as well as improvements in efficiency. The use of frequency down conversion by divalent Sm/Eu and trivalent Yb/Tb halides embedded in the protective coatings of the solar cells to increase the efficiency of photovoltaic conversion will be investigated. The predicted ideal efficiencies are greater than 50%.
During Phase I we will determine the optimal layer thicknesses, doping profiles and current density matching requirements for two-terminal multiple-heterojunction solar cell designs. We will grow HgCdZnTe layers with Zn composition ≈ 0.5 on a Si substrate using a thin CdTe/ZnTe strained-layer superlattice to eliminate cracking and minimize strain, will optimize the growth of HgCdMgTe, and will measure mobilities and minority carrier lifetimes in the layers. We will fabricate and test a two-junction solar cell. Frequency down conversion will be demonstrated, progress toward its optimization will be made, and optical fusion of the solar cell and protective layers will be investigated.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The proposed solar cells are expected to have ~40% efficiencies and <150 g/m2 densities without protective layers if the Si substrates are removed. This would give mass specific powers of ~3600 W/kg without a protective coating, far in excess of NASA requirements, or would allow one to meet the NASA mass specific power requirement with a protective coating having a density of ~0.07 g/cm2 (a thickness of ~175 ìm for typical protective coating materials). The proposed solar cells also would function across a very broad range of temperatures. Thus, the proposed solar cells would be potentially appropriate for powering all off-Earth NASA observation platforms: Earth orbiting spacecraft, planetary spacecraft, balloons, aircraft and unmanned aerial vehicles (UAVs). They also would be appropriate for powering ground and marine based observation platforms because of their ultra-high efficiencies, but they would face competition from other high-efficiency solar cell technologies not appropriate for off-Earth use.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The proposed solar cells have obvious potential applications for powering both military and intelligence-gathering satellites and commercial communication satellites because of their expected high efficiencies and mass specific power. They also have a broad potential application for powering off-Earth sensors and focal plane arrays for the MDA and for various Air Force applications, including unmanned aerial vehicles (UAVs), as well as on-Earth applications requiring ultra-high efficiency solar cells. The proposed down-conversion technology using divalent Sm and trivalent Yb and Tb halides embedded in the protective coatings of the solar cells will have even a much larger potential application. It could be applied with fluorozirconate glass coverings or other coverings for improving the efficiency of any on-Earth solar cell.

NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.

TECHNOLOGY TAXONOMY MAPPING
Photovoltaic Conversion


Form Generated on 09-18-07 17:50