Radiation Resistant Elastomer Containing POSS, Phenylsiloxane and Ce(IV) Compositions for a Space Solar Cell Adhesive

This SBIR Phase II program will develop a space solar cell adhesive that will lose less than 3% transmittance from 400 nm to 2000 nm after 15 years in geosynchronous or medium earth orbit. In order to achieve this, transmission, adhesion, and proton-, electron- and UV-resistance must all be improved. The current standard, DC-93500, is vulnerable to proton attack, but Oxazogen’s adhesives are based upon novel patented hyperbranched POSS elastomers where phenyl content can be precisely controlled to achieve optimum proton resistance, while Ce(IV) isopropoxide levels can be controlled to achieve optimum UV resistance. As well as being used to bond cover glasses to solar cells, these materials also have the ultimate potential to replace the cover glasses altogether, resulting in lower weight cells, more densely packed cell arrays, reduced arcing and significant cost savings. Oxazogen’s commercial partner, EMCORE Photovoltaics, Inc., holds 50% of the global market share in space solar cells. During Phase I, Oxazogen developed formulations with excellent transmittance and adhesive performance, and EMCORE performed radiation-resistance testing. During Phase II, adhesive and coating formulations will be optimized, and used to fabricate and to test the performance of prototype EMCORE space solar cells with and without cover glasses. BENEFIT: The adhesives and coatings developed in this Phase II SBIR will generate revenues through materials sales and patent licensing. With the increasing effort on space applications by the military and increasing emphasis by NASA on space exploration the market for solar adhesives will continue to assume ever increasing importance and the growth is expected to accelerate in the years to come. The market is driven by an ever-increasing demand for lower weight, higher efficiency across a wider range of wavelengths, and better durability and end-of-life (EOL) performance. This technology has dual-use in military satellites, and in civilian communication, television broadcasting, weather forecasting and global position systems (GPS) satellites in medium earth or geosynchronous orbits. It also has the potential to protect terrestrial electrical components (e.g., power supplies, relays, cable connectors) and electronics (e.g., assemblies and circuit boards) from temperature extremes, high humidity, thermal shock and radiation.