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Posted: October 27, 2006
Trying to break through the current technological hurdles of solar energy
(Nanowerk News) Arizona State University (ASU) scientists Rudy Diaz and Stuart Lindsay will lead a research group on a three-year, $1.1 million grant from the National Science Foundation for an innovative project designed to break through the current technological hurdles of solar energy.
Today's solar panels, made up of thousands of individual solar cells, are extremely inefficient and costly to produce, limiting Sun Belt states such as Arizona from fully using their most abundant renewable energy resource.
“Over the past decade, ASU has quietly reassembled one of the most comprehensive portfolios of solar-related research programs in the world,” says Jonathan Fink, vice president of ASU's Office of Research and Economic Affairs. “This new award is a prime example of ASU's interdisciplinary approach to solar research and uncovering new ways to better harness, create and utilize solar energy.”
Diaz and Lindsay have assembled a group of scientists across ASU into a NSF-funded Nanoscale Interdisciplinary Research Team. 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 professor of physics in the College of Liberal Arts and Sciences and director of the Biodesign Institute's Center for Single Molecule Biophysics.
The 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 harness just 10 percent 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 shedding more heat than light. One part of the project will focus on developing better light-gathering capabilities. Diaz is 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 also are 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, 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 research 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,” Diaz says.
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, faculty members 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,” Lindsay says. “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 ASU team's end result will be an attempt to create new solar energy technology platforms and attract the interest of future research partners.