Photovoltaics & Nanomaterials
June 21, 2007
Dr. Sheila Bailey, who has a phenomenal number of publications in her field, talked to us about solar power cells and the physics and chemistry of their design. She’s officially an electrical engineer here at GRC, but she says she’s actually a physicist—it’s just that engineers get paid more.
The PowerPoint began with slides of her travels and her family, inspired by the Academy’s profile book, she said. She has three adult children, who are accumulating advanced degrees in disciplines all across the map. Impressively, she stopped working to raise them, living at home on her farm for ten years before picking up work again. But an education never goes away, she told us, and even though she needed some re-training, she and her Ph.D. got a job at NASA. She’s also been to at least 99 countries, and when she was the chair of the World Conference on Photovoltaic Energy Conversion in May, 2006, she decided to have it on the big island of Hawaii. She clearly knows how to balance work and a life outside it.
Regarding photovoltaics, she discussed methods of improving efficiency and lowering cost, since NASA is becoming more concerned with the latter as its funding shrinks, with much of the remainder concentrated on Ares and Orion instead of solar power. One way to improve a solar panel’s efficiency is to stack several of them, especially if the crystal structures of adjacent layers are adjusted to match each other.
Another way involves a technique Bailey pioneered: quantum dots. She puts tiny lumps of certain fluorescent semiconductors in the crystal lattice, where they absorb alpha particle radiation that could otherwise harm the panel. They then give off light the panel can use for energy, so it’s possible to strap radioactive material to the panels of deep space probes for power during low-light parts of the journey. Quantum dots made of different materials glow different colors in response to alpha radiation, so the dots can be tuned to suit the panel.
Dr. Bailey forgot her example solar cells in her office, but she invited us to stop by and see them or have a tour of the facilities.