WEDNESDAY 09 FEBRUARY, 2011 |
Waffle Solar Cells And Plasmonics
Through an emerging branch of technology called plasmonics, the study of the
interaction of light and metal, a team of Stanford researchers believe they can
more effectively trap light within thin solar cells using a honeycomb
"waffle" type approach.
In plasmonics, high-frequency, dense electrical waves are created instead of
electron particles, travelling in extremely fast waves like sound through the
air. The effect can only be created under precise circumstances.
In order to create the world's first plasmonic dye-sensitized solar cell,
Michael McGehee , associate professor of materials science and engineering at
Stanford Univerity and his team applied titania, which a semi-porous metal also
transparent to light, to a transparent, electrically conductive base.
Next, a honeycomb pattern of nanoscale dimples was created using equipment akin
to a waffle iron, which consisted of tiny silicon nanodomes, each about 300 nanometers in diameter and 200 nanometers
high. As a point of comparison, a human hair is about 60000 nanometers in diameter.
A light-sensitive dye was poured over the "waffle" material, creating
a thin layer in the pores and dimples. A layer of silver was then applied; the
end result being a pattern of tiny domes on the side of the silver that would
face a light source.
The nanodomes help reflect unabsorbed light back into the dye for more efficient
collection and light interacting with the silver nanodomes produces plasmonic
effects. It's an exact process, with the nanodomes needing to be a particular
size and spacing to produce an optimal plasmonic reaction.
Professor McGehee says that by utilising plasmonics, light can be better
absorbed in thinner solar
than ever before.
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