Write your abstract here.Silicon
nanoparticles enhance performance of solar cells.
August 22nd, 2007.
Placing
a film of silicon
nanoparticles onto a silicon solar cell can boost
power, reduce heat and prolong the cell’s life, researchers now report.
“Integrating a high-quality film of silicon nanoparticles 1
nanometer in size directly onto silicon solar cells improves power
performance by 60 percent in the
ultraviolet range of the spectrum,”
said Munir Nayfeh, a physicist at the University of Illinois and
corresponding author of a paper accepted for publication in Applied
Physics Letters.
A 10 percent improvement in the visible range of the spectrum can be
achieved by using nanoparticles 2.85 nanometers in size, said Nayfeh,
who also is a researcher at the university’s Beckman Institute.
In conventional solar cells, ultraviolet light is either filtered
out or absorbed by the silicon and converted into potentially damaging
heat, not electricity. In previous work, however, Nayfeh showed that
ultraviolet light could efficiently couple to correctly sized
nanoparticles and produce electricity. That work was reported in the
August 2004 issue of the journal Photonics Technology Letters.
To make their improved solar cells, the researchers began by first
converting bulk silicon into discrete, nano-sized particles using a
patented process they developed. Depending on their size, the
nanoparticles will fluoresce in distinct colors.
Nanoparticles of the desired size were then dispersed in isopropyl
alcohol and dispensed onto the face of the solar cell. As the alcohol
evaporated, a film of closely packed nanoparticles was left firmly
fastened to the solar cell.
Solar cells coated with a film of 1 nanometer, blue luminescent
particles showed a power enhancement of about 60 percent in the
ultraviolet range of the spectrum, but less than 3 percent in the
visible range, the researchers report.
Solar cells coated with 2.85 nanometer, red particles showed an
enhancement of about 67 percent in the ultraviolet range, and about 10
percent in the visible.
The improved performance is a result of enhanced voltage rather than
current, Nayfeh said. “Our results point to a significant role for
charge transport across the film and rectification at the nanoparticle
interface.”
The process of coating solar cells with silicon nanoparticles could
be easily incorporated into the manufacturing process with little
additional cost, Nayfeh said.
Source: University of Illinois at Urbana-Champaign