NASA STTR 2009 Solicitation

FORM B - PROPOSAL SUMMARY


PROPOSAL NUMBER: 09-2 T3.01-9972
PHASE 1 CONTRACT NUMBER: NNX10CF61P
RESEARCH SUBTOPIC TITLE: Technologies for Space Power and Propulsion
PROPOSAL TITLE: Nanowire Photovoltaic Devices

SMALL BUSINESS CONCERN (SBC): RESEARCH INSTITUTION (RI):
NAME: Firefly Technologies NAME: Rochester Institute of Technology
STREET: 2082 Hackberry Lane STREET: 111 Lomb Memorial Drive
CITY: Shakopee CITY: Rochester
STATE/ZIP: MN  55379 - 4622 STATE/ZIP: NY  14623 - 5608
PHONE: (608) 698-0935 PHONE: (330) 421-2104

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
David Forbes
dvfsps@rit.edu
111 Lomb Memorial Drive
Rochester, NY 14623 - 5608
(330) 421-2104

Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 3
End: 5

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
Firefly, in collaboration with Rochester Institute of Technology, proposes developing a space solar cell having record efficiency exceeding 40% (AM0) by the introduction of nanowires within the active region of the current limiting sub-cell. The introduction of these nanoscale features will enable realization of an intermediate band solar cell (IBSC), while simultaneously increasing the effective absorption volume that can otherwise limit short-circuit current generated by thin quantized layers. The triple junction cell follows conventional designs comprised of bottom Ge cell (0.67eV), a current-limiting middle GaAs (1.43eV) cell, and a top InGaP (1.90eV) cell. The GaAs cell will be modified to contain InAs nanowires to enable an IBSC, which is predicted to demonstrate ~45% efficiency under 1-sun AM0 conditions. The InAs nanowires will be implemented in-situ within the epitaxy environment, which is a significant innovation relative to conventional semiconductor nanowire generation using ex-situ gold nanoparticles. Successful completion of the proposed work will result in ultra-high efficiency, radiation-tolerant space solar cells that are compatible with existing manufacturing processes. Significant cost savings are expected with higher efficiency cells, enabling increased payload capability and longer mission durations.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The high efficiency (>40%) of the proposed PV cell will make it the obvious choice for NASA space-based applications. Another potential application revisits a NASA research thrust on virtual substrates. One important aspect of nanowires is the demonstrated capability to integrate widely mismatched nanowires and substrates. The restricted cross-sectional area of the nanowire reduces the opportunity for mismatch defect generation. Nanowires of highly mismatched systems (>7%) have been demonstrated in the literature and, more importantly, in the Phase 1 of this proposal. This flexibility in substrate/nanowire combinations can enable more optimum bandgap and material combinations for novel devices. Incorporating nanowires onto a recrystallized Ge/metal foil substrate would potentially solve the problem of grain boundary shunting of generated carriers by restricting the cross-sectional area of the nanowire (10s of nms diameter) to sizes smaller than the recrystallized grains (0.5-1 um2). In this approach, the nanowire PV device integrated with a low-cost foil substrate would have potential for high weight-specific power (W/kg).

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The high-efficiency of the proposed device represents a significant competitive advantage for any space-based power generation application. This proposed device offers a significant increase in efficiency which corresponds to a significant cost savings in terms of photovoltaic array size, array weight, and launch costs. The proposed cells would represent a disruptive technology within the space photovoltaic marketplace. Additionally, a path is proposed for commercial, low-cost nanowire growth with broad market implications. Nanowires of highly mismatched systems (>7%) have been demonstrated in the literature and, more importantly, in the Phase 1 of this proposal. This flexibility in substrate/nanowire combinations enables more optimum bandgap and material combinations for novel devices. One exciting possibility is the integration of III-V nanostructures on low-cost silicon substrates for photovoltaic applications. In addition, the use of core-shell geometry for photovoltaic applications decouples the absorption length from the carrier collection length, which allows low diffusion length material to be effective PV materials in the core-shell configuration.

TECHNOLOGY TAXONOMY MAPPING (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.)
Energy Storage
Optical
Optical & Photonic Materials
Photonics
Photovoltaic Conversion
Power Management and Distribution
Radiation-Hard/Resistant Electronics
Renewable Energy
Semi-Conductors/Solid State Device Materials


Form Generated on 02-01-11 15:25