Novel Environmental Protection for Multi-Junction Solar Cells

ABSTRACT: Thin film flexible cells based on IMM architecture require a protective optical coating that maintains optical and mechanical integrity when rolled and unrolled for deployment. The multi-functional coating will be deposited on flexible substrates such as polymers and thin glass, and the combination must be stable to the space environment, namely: temperature changes, ionizing radiation, and atomic oxygen, while providing ESD protection. Stability to ground-storage humidity is also necessary. Our team will apply the radiation resistant and space qualified deposition process and materials technology that we established and demonstrated on previous SBIR and other R & D projects. Samples of our UVR, wide band AR, and ESD coatings on flexible polymer substrates flown on MISSE-7 suffered little or no loss of transmission. A larger number of candidate substrate materials will be coated, and their properties more extensively evaluated. Integrated assemblies consisting of functional cells and coated covers will be subjected to simulated space environmental exposure elements, and the effect on power output will be evaluated. Compatibility with cell integration and assembly procedures for panel construction will be addressed. The new coating and substrate combinations will be useful for all DoD, NASA, and communications spacecraft power, and terrestrial applications that employ flexible arrays. BENEFIT: The ability to package and stow solar cell arrays in a rolled configuration provides large reductions power-per-weight and power-per-volume performance. Coupled with higher solar energy conversion efficiencies, flexible MJ IMM cells will soon replace conventional arrays. Our flexible optical and protective coating will maximize photon throughput to the solar cell and protect the assembly from the harsh space environment. The new coatings developed in the proposed effort can be applied to all DoD, NASA, and communications spacecraft power, and terrestrial applications that employ flexible arrays.