Radiation Resistant and Conformable Polyhedral Oligosilsesquioxane (POSS) Protective Coatings for Flexible Space Solar Cells

This SBIR Phase I program will develop a flexible space solar cell coating that will lose less than 5% transmittance from 350 nm to 2000 nm after 15 years in geosynchronous orbit or 5 years in low earth orbit. The current standard space solar cell sealing material, DC-93-500, is vulnerable to proton and atomic oxygen attack, and current solar cells require rigid multilayer stacks in order to function. Oxazogen’s coatings are based upon novel patented polyhedral oligosilsesquioxane (POSS) hyperbranched elastomers where the resistance of POSS to atomic oxygen attack is well-known, and where Oxazogen materials have already been demonstrated to have excellent resistance to proton, electron and UV radiation, thermal cycling, humidity, and out-gassing in space adhesive applications. The coating formulation is inexpensive, simple to apply, and has a long shelf life. Oxazogen has an established commercial partnership with EMCORE Photovoltaics, Inc., a solar cell manufacturer holding half of the global market share in space solar cells. During Phase I, Oxazogen will develop conformable POSS-hyperbranched polymer coatings formulations with excellent transmittance, thermal and mechanical properties, and EMCORE will perform radiation resistance testing. During Phase II, the coating formulations will be optimized, further qualified, and commercialized in collaboration with EMCORE. BENEFIT: The coatings developed in this Phase I SBIR will generate revenues through materials sales and patent licensing. With the increasing focus on space applications by the military and increasing emphasis by NASA on space exploration, the market for flexible multi-junction space solar cells will continue to assume increasing importance, and the growth of the market is expected to accelerate in the years to come. The market is driven by an ever-increasing demand for lower weight, higher efficiency and higher specific power 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 communications, television broadcasting, weather forecasting and global positioning systems (GPS) satellites in low earth, medium earth or geosynchronous orbits. It also has the potential to protect telescope sun shields in low earth orbit, terrestrial solar concentrator systems and terrestrial organic photovoltaic systems from UV radiation, and 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.