A team of scientists from Arizona State University has received a three-year, $1.1 million grant from the National Science Foundation to create nanoscale devices that better exploit the energy from one of Arizona's most abundant resources -- sunlight. ASU scientists Rudy Diaz and Stuart Lindsay are heading the project, and have assembled a group of ASU scientists into an NSF-funded Nanoscale Interdisciplinary Research Team (NIRT). Diaz is an associate professor in the Department of Electrical Engineering and WINTech/Connection One in the Ira A. Fulton School of Engineering, and Lindsay is a physics professor and director of the Biodesign Institute's Center for Single Molecule Biophysics. Today's solar panels, made up of thousands of individual solar cells, are extremely inefficient and costly to produce. The ASU team's goal is to create nanoscale devices for higher efficiency solar energy and photonics applications. This so-called "bottom up" approach to nanotechnology promises to take on the challenges of solar energy research by building devices atom by atom at a scale a thousand times finer than the width of a human hair. In every solar cell, light energy, measured in the billions of photons that hit a square centimeter patch of the cell every second, is converted to electricity. But even the most advanced solar cells can only harness 10 to 30 percent of the available sunlight energy. The majority of the energy is lost, and simply escapes as heat. The ASU researchers hope to make progress by, in this case, shedding more heat than light. One part of the project will focus on developing better light gathering capabilities. Diaz is currently working on the fabrication of a photonic antenna, a device that he says will increase the number of light photons absorbed through a solar cell, thereby boosting the rate of energy production. But other improvements are also needed. Once the photons are captured, the light energy is absorbed by electrons, producing a charge in the process and generating electricity. Separating and guiding the charge along a circuit poses a difficult technical challenge. According to Diaz, in order to take greater advantage of light-gathering antennae, it is necessary to directly assemble and position them adjacent to light-absorbing molecules at nanometer-scale precision. The team's novel approach focuses on the molecule of life, DNA. "One of the ways we can do this is by using manufactured DNA to create self-assembling strands on which the charge can travel," said Diaz. One researcher in Lindsay's center, Hao Yan, is an expert in the burgeoning science of DNA nanoarchitecture -- or molecular scale DNA origami -- for folding DNA into a broad range of technological applications important for human health and bioelectronic sensing devices. By controlling the exact position and location of the chemical bases within a synthetic replica of DNA, Yan can potentially fashion an unlimited variety of DNA assemblies. Yan and professor Devens Gust, both faculty in the Department of Chemistry and Biochemistry, will help the team create self-assembled DNA structures to attract and harness a greater degree of solar energy and light photons. "The DNA will act as the scaffold that holds everything together," said Lindsay. "It will hold the antenna that gathers light together with the molecules that convert the intensified light to electricity. The antenna, by concentrating light, will increase the rate of absorption of the light photons." The team's end result will attempt to create new solar energy technology platforms and attract the interest of future research partners. The NSF project is part of the agency's Grant Opportunities for Academic Liaison with Industry (GOALI) award program, which recognizes and promotes interdisciplinary research between education and industry. For more information, visit: www.asu.edu
Photosensitizers