NASA SBIR 01-II Solicitation

FORM 9B - PROPOSAL SUMMARY


PROPOSAL NUMBER: E2.07-8465 (For NASA Use Only - Chron: 013534 )
PHASE-I CONTRACT: NAS3-02027
PROPOSAL TITLE: Wide-Bandgap CIAS Photovoltaic Absorber on Flexible Substrates

TECHNICAL ABSTRACT (LIMIT 200 WORDS)
Thin-film photovoltaic cells offer the promise of high specific power arrays for space applications. Two thin-film photovoltaics technologies are presently vying for use in space applications; copper-indium-gallium-diselenide (CIGS), and amorphous silicon. This proposal focuses on efficiency improvements to the CIS-alloy technologies by the continued development of a third possibility, copper-indium-aluminum-diselenide (CIAS). This wide-bandgap thin-film technology will be deposited by co-evaporation at low substrate temperatures on sub-bandgap light transparent back contacts and lightweight, flexible and sub-bandgap light transparent polyimide substrates. To achieve the optimum bandgap of about 1.45 eV for the space solar spectrum, less than half the amount of aluminum (Al) is needed in CIAS, then gallium (Ga) in CIGS. Thus, using Al may avoid a concentration limit (bandgap limit) similar to the amount of Ga in CIGS for the degradation of material electrical quality due to Ga-Ga defect complexes. Other advantages of the proposed technology include: higher-efficiency modules due to lower resistive and distributed diode losses; higher-efficiency modules at higher operating temperatures due to more favorable temperature coefficients of cell parameters and complete IR transmission; potential for backside array visible light collection, and high end-of-life-efficiency modules due to inherent charged particle radiation resistance of CIS based alloys.

POTENTIAL COMMERCIAL APPLICATIONS
Higher specific power space arrays allow more mission capability by reducing the weight of the space array and thereby allowing more satellite functionality or higher power arrays for additional satellite capability. Due to the large increase of specific power available with thin-film technologies on flexible substrates versus the present single crystal array technology, ITN Energy Systems expects significant commercial and government satellite array business to become available. The application of wide-bandgap CIAS absorber layers with transparent back contacts and substrates to the present thin-film technology will potentially boost performance over CIGS baseline by as much as 84% and provide additional leverage of this technology to satellite manufacturers. In addition high voltage solar array applications are available when combined with the proposed monolithic integration for these arrays. Furthermore, the wide-bandgap and transparent back contact technology developed herein, will be enabling for next generation thin-film tandem junction photovoltaic (PV) technology. Together with ITN?s existing program on durable bottom cells using low bandgap CIS, then the essential components for realizing these high-efficiency and high-voltage devices will be in place.

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR (Name, Organization Name, Mail Address, City/State/Zip)
Lawrence Woods
ITN Energy Systems, Inc.
8130 Shaffer Pkwy.
Littleton , CO   80127 - 4107

NAME AND ADDRESS OF OFFEROR (Firm Name, Mail Address, City/State/Zip)
ITN Energy Systems, Inc.
8130 Shaffer Pkwy.
Littleton , CO   80127 - 4107


Form Printed on 05-09-02 16:37