08:44 Blooming
Post
http://www.bloomingpost.com/2015/03/a-fully-transparent-solar-cell-that.html
Researchers at
Michigan State University have created a fully transparent solar concentrator,
which could turn any window or sheet of glass (like your smartphone’s screen)
into a photovoltaic solar cell. Unlike other “transparent” solar cells that
we’ve reported on in the past, this one really is transparent, as you can see
in the photos throughout this story. According to Richard Lunt, who led the research,
the team are confident that the transparent solar panels can be efficiently
deployed in a wide range of settings, from “tall buildings with lots of windows
or any kind of mobile device that demands high aesthetic quality like a phone
or e-reader.”
Scientifically,
a transparent solar panel is something of an oxymoron. Solar cells,
specifically the photovoltaic kind, make energy by absorbing photons (sunlight)
and converting them into electrons (electricity). If a material is
transparent, however, by definition it means that all of the light passes through the
medium to strike the back of your eye. This is why previous
transparent solar cells have actually only been partially transparent
— and, to add insult to injury, they usually they cast a colorful shadow too.
To
get around this limitation, the Michigan State researchers use a slightly
different technique for gathering sunlight. Instead of trying to create a
transparent photovoltaic cell (which is nigh impossible), they use a transparent
luminescent solar concentrator (TLSC). The TLSC consists of organic
salts that absorb specific non-visible wavelengths of ultraviolet and
infrared light, which they then luminesce (glow) as another wavelength of
infrared light (also non-visible). This emitted infrared light is guided to the
edge of plastic, where thin strips of conventional photovoltaic solar cell
convert it into electricity. [Research paper: DOI:
10.1002/adom.201400103- "Near-Infrared Harvesting Transparent
Luminescent Solar Concentrators"]
If you look closely, you can see a couple of black strips along the edges of plastic block. Otherwise, though, the active organic material — and thus the bulk of the solar panel — is highly transparent. (Read: Solar singlet fission bends the laws of physics to boost solar power efficiency by 30%.)
Michigan’s
TLSC currently has an efficiency of around 1%, but they think 5% should be
possible. Non-transparent luminescent concentrators (which bathe the room in
colorful light) max out at around 7%. On their own these aren’t huge figures,
but on a larger scale — every window in a house or office block — the numbers
quickly add up. Likewise, while we’re probably not talking about a technology
that can keep your smartphone or tablet running indefinitely, replacing
your device’s display with a TLSC could net you a few more minutes or hours of
usage on a single battery charge.
The
researchers are confident that the technology can be scaled all the way from
large industrial and commercial applications, down to consumer devices, while
remaining “affordable.” So far, one of the larger barriers to large-scale
adoption of solar power is the intrusive and ugly nature of solar panels —
obviously, if we can produce large amounts of solar power from sheets of
glass and plastic that look like normal sheets of glass and plastic, then that
would be big.
