SBIR Phase I: Thin Silicon Solar Cells for Aerospace Applications

The broader impact of this Small Business Innovation Research (SBIR) Phase I project is to enable the emerging and rapidly growing markets of solar powered aerospace devices. The solar array is often the most expensive component of satellites, drones and airships and reducing their cost 10 times while also reducing the weight 5 times and making solar cells flexible can disrupt one of the main barriers for the growing private aerospace economy. The major target market for thin silicon solar cells is the constellations of thousands of new satellites at the lower earth orbit for providing Global Satellite Internet and IoT device communications. Global Internet can make a broader impact on the human life in three areas: (1) enable worldwide communications, (2) stimulate economic growth in developing countries by providing Internet connection, (3) establish more sustainable societies by providing access to education, ensuring the freedom of speech and providing the instruments for electronic democracy. Another major target market is drones for surveillance and remote monitoring and airships for cargo transportation. In the future, thin silicon solar cells can become the ultimate source of energy for solar powered space transportation, asteroid mining and colonization of Mars and the Moon. The proposed project will develop two innovations which can enable mass production of thin Si solar cells for aerospace applications. There are two main roadblocks for using thin Si solar cells commercially. First, is that efficiency of thin silicon cells drops by 4-6%. Second, is that 10-micron-thick Si wafers cannot be manufactured using standard Si solar cell fabrication methods. Regher Solar has developed two innovations to enable mass production of thin Si cells with >20% efficiency. The first innovation is processing of 10-micron-thick on thicker Si wafers to use them for handling. The second innovation is using silicon heterojunction technology with copper metallization, which achieves the highest efficiency when the cell is only 10 microns thick. The overall goal of this SBIR proposal is to develop lower cost, high efficiency, flexible, reliable and manufacturable solar cells based on thin Si technology for the rapidly growing market of solar powered aerospace devices. The specific goals of this Phase I project are: (1) finalize a process flow, (2) achieve >22% AM0 efficiency, >2000 W/kg specific power, >200 W/m2 power density on a 10-micron-thick wafer; (3) conduct a comprehensive reliability testing of thin Si solar cells; (4) demonstrate flexible blankets. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.