Transparent Conductor for Ultra High Efficiency Solar Cells for Space Applications

ABSTRACT: The Air Force has established a target of making space photovoltaic (PV) systems, lighter, less complex but also more efficient, robust and lower cost than present generation space cells. With multi-junction cells being the candidate of choice, Eclipse proposes to optimize and demonstrate its transparent conductor technology (EclipseTEC/PVTEC) materials as a new electrode, displacing expensive other conductors (such as indium-tin oxide) used in many thin film devices, with the benefit of being able to be tailored to maximize transmission at precise UV, visible, and near IR wavelength(s) of interest. In this program, Eclipse Energy Systems proposes to optimize its visibly transparent metal-like self-structured conductor with plasmonic waveguide effect technology as a superior, low cost conductor for solar cells. During the phase II effort, the Eclipse PVTEC will be matured via modeling and process optimization for one or more specific PV multi-junction cells. The goal of the program is to minimize the absorption and reflection of the top surface PV metallization system and maximize the efficiency of each PV cell. Metallization absorption of ~2-3% or less, 100 ohms/sq sheet resistance and transmission of 80% or better (95%+ as a goal) at the wavelengths of interest. BENEFIT: The commercialization of the PVTEC conductor could go into many markets including space, military, civilian and domestic power application for utility power. Eclipse"s initial partnership is with Emcore to replace their metal based cell metallization with PVTEC. This could increase the efficiency of the cell to about 34%. This would reduce array size and overall weight of the satellite system. The volume of this marked is projected to increase as shown in Figure C1. Eclipse would provide the technology through some type of licensing agreement with Emcore. Equipment and manufacturing process development for manufacturing would be done jointly by Eclipse and Emcore. For terrestrial applications the PVTEC metallization could be designed to fit several terrestrial solar cells giving increased efficiency. Emcore is in the terrestrial solar cell business too, so we could easily transition to that type of cell. Most of these systems are utility based for power generation. At a time when we have completed our work on space cells, we will endeavor to look at the terrestrial cell business. Further applications could be made with other makers of solar cells, but this would require new agreements to be cast. Overall concentrating solar cell market trends are given in Table C1 through 2015.