Cory Nelson

Harvesting Sunlight with Quantum Dots

By Stacy Kish on August 4, 2010

Clean, renewable solar energy is a promising alternative energy source, but current photovoltaic cells only collect incoming solar radiation with 31 percent efficiency. Cory Nelson explains, “Solar cells cannot collect the entire spectrum of solar energy, missing the lowest energy.” The higher energy solar light that is captured relaxes before it can be used. “During the relaxation process, some of the energy is lost to heat and other decay processes,” said Nelson.

Nelson, a doctoral candidate at the University of Texas, Austin and a DOE Office of Science Graduate Fellow, is working to resolve these problems and improve solar cell efficiency. “My research is focused on trying to figure out how to extract this energy without loses from heat and to collect energy at more wavelengths.”

To accomplish this task, Nelson is working with quantum dots. “Quantum dots are semiconductor nanocrystals that are around 1 billionth of a meter in size, giving them novel properties which could be used to extract electrons efficiently,” explains Nelson. These tiny materials allow us to match the absorption to the sun and slow the electron relaxation. “A breakthrough in this area could double the efficiency of solar cells,” said Nelson.

Nelson was drawn to the fundamental nature of this research. “I found this research very exciting because it involves understanding physical processes at the most basic level,” he said.

He concludes, “This fellowship will open many opportunities by making it possible to attend more research conferences where I can not only present my research, but talk to other experts in the field.” Nelson’s graduate fellowship is funded by the American Recovery and Reinvestment Act of 2009.

Stacy Kish is a Science Writer with the Office of Science.