Plasmonics study suggests how to maximize production of ‘hot electrons’
(July 23, 2015) New research from Rice University could make it easier for engineers to harness the power of light-capturing nanomaterials to boost the efficiency and reduce the costs of photovoltaic solar cells.
Although the domestic solar-energy industry grew by 34 percent in 2014, fundamental technical breakthroughs are needed if the U.S. is to meet its national goal of reducing the cost of solar electricity to 6 cents per kilowatt-hour.
In a study published July 13 in Nature Communications, scientists from Rice’s Laboratory for Nanophotonics (LANP) describe a new method that solar-panel designers could use to incorporate light-capturing nanomaterials into future designs. By applying an innovative theoretical analysis to observations from a first-of-its-kind experimental setup, LANP graduate student Bob Zheng and postdoctoral research associate Alejandro Manjavacas created a methodology that solar engineers can use to determine the electricity-producing potential for any arrangement of metallic nanoparticles.
LANP researchers study light-capturing nanomaterials, including metallic nanoparticles that convert light into plasmons, waves of electrons that flow like a fluid across the particles’ surface. For example, recent LANP plasmonic research has led to breakthroughs in color-display technology, solar-powered steam production and color sensors that mimic the eye.
“One of the interesting phenomena that occurs when you shine light on a metallic nanoparticle or nanostructure is that you can excite some subset of electrons in the metal to a much higher energy level,” said Zheng, who works with LANP Director and study co-author Naomi Halas. “Scientists call these ‘hot carriers’ or ‘hot electrons.’”
Halas, Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering, said hot electrons are particularly interesting for solar-energy applications because they can be used to create devices that produce direct current or to drive chemical reactions on otherwise inert metal surfaces.