To help NASA better explore outer space, Yuji Zhao headed to Capitol Hill with NASA’s best and brightest collaborators in academia to talk space tech with U.S. Congress members.
Zhao, an assistant professor of electrical and computer engineering at Arizona State University’s Ira A. Fulton Schools of Engineering, was one of only three faculty members from across the country invited to join NASA’s senior leadership in the nation’s capital for NASA Tech Day on November 29, 2017.
The important research Zhao presented involves high-temperature solar cell technology for missions that head to the very hot planet Mercury.
This is made possible by Zhao’s work with gallium nitride, which has enabled devices such as solar cells to sustain their performance in very high temperatures
“One major breakthrough is we can develop a solar cell that has improved performance over high temperatures, whereas the silicon cells we have now would degrade with higher temperatures,” Zhao said.
Silicon-based solar cells at room temperature (20–25 degrees Celsius, 68–77 degrees Fahrenheit) operate at 80 percent capacity, but at 80 degrees Celsius or 176 degrees Fahrenheit it degrades to 20 percent, Zhao said.
Gallium nitride based solar cells, however, operate at 50 percent capacity at room temperature and all the way at 300 degrees Celsius or 572 degrees Fahrenheit they operate at 80 percent capacity.
“This is quite exciting and we are working with several groups here as well as at Stanford University to figure out the fundamentals behind [gallium nitride],” Zhao said. “The whole result is very interesting and NASA has high regard for those results.”
Zhao has also been using gallium nitride to power electronics as part of research supported by NASA as well as the Department of Energy’s Advanced Research Projects Agency-Energy and the Department of Defense’s Defense Threat Reduction Agency. Zhao has also received the NASA Early Career Faculty Award and participated in the NASA HOTTech Program.