■ Organic Photonics
Such materials also enable higher-power conversion efficiencies compared
to traditional fullerene acceptors. As a
result, OSC efficiencies are now reaching
over 12 percent — a value that has long
been considered a significant threshold in
efficiency for commercial applications.
OSCs can be produced in different
colors, transparencies and shapes, which
allow for unique design flexibility and
enable new ways of thinking about solar.
This offers the opportunity to unlock
the huge potential for solar windows and
facades in the architectural sector.
Despite recent improvements regarding
power conversion efficiency and stability,
there are still challenges ahead and more
work to be done.
“Researchers are continuously pro-
gressing in increasing the stability of
OSC by studying the factors limiting
the stability, designing new material and
device engineering,” Bischoff said. “This
will provide a solution to move OSC
technologies from today’s niche market
At U.K.-based Eight19, the target
gap in the market is environmentally
friendly indoor PV efficiency lighting.
Unlike crystalline silicon solar cells,
which are typically found on rooftops and
large-scale installations, OPV materials
perform very well under indoor lighting
Recently, the company demonstrated
efficiencies of over 14 percent under 1000
Lux LED lighting, and the potential is
there to take this to over 25 percent or
more in the very near future. Harvesting energy from indoor lights opens up
interesting options in areas such as sensor
networks, the Internet of Things and
the retail sector. In the retail sector, for
example, energy could be provided for
electronic shelf labels and other point-of-sale signs.
“The option of using just the energy
harvested from lighting in combination
with a small rechargeable battery or even
a capacitor is very attractive in situations where comparatively small amounts
of power are required in environments
where replacing batteries or main electricity connection are costly and challenging,” said Jurjen F. Winkel, technology
manager at Eight19.
Even outdoors, the flexibility, robust-
ness and low weight-to-performance
could one day offer some interesting
opportunities in developing countries,
where shipping costs and basic infrastruc-
tural challenges make transportation and
mounting of traditional silicon panels
costly and impractical.
Experts are confident that the next
couple of years will see OPV products in
the marketplace and that once niche positions are established, continuous improvement will lead to the wider adoption of the
Li-Fi goes organic
Move aside Wi-Fi, the future of wireless communication could be Li-Fi, as
scientists in the U.K. make promising
initial demonstrations thanks to organic
photonics. Researchers from the Universities of Edinburgh, Oxford and Strathclyde
worked together to show that light can be
used to send and receive communication
through the air.
“The general attractive features of
organic materials for photonics are the
ability to tune the properties by adjusting
the structure and simple fabrication of
devices by evaporation or spin coating,”
said professor Ifor Samuel of the University of St. Andrews.
In the setup, LED lighting is modulated
to send information to receivers such as
phones and laptop computers. Transmitters are currently challenged by the fact
that white LEDs actually consist of a blue
LED combined with a phosphor color
converter. The phosphor has a long
“excited state” lifetime, which limits the
modulation bandwidth and hence the data
“We have shown that the short excited
state lifetime of organic semiconductors
can overcome this limitation, enabling
greater than 1-gigabit-per-second communication rates,” Samuel said.
On the receiver side, the challenge is
to be sensitive but fast. Here the group
showed that fluorescent concentrators can
provide fast large-area receivers.
Currently the idea is to use optical
communication to supplement Wi-Fi, but
in the future, as the impending radio frequency spectrum “crunch” really begins
to bite, Samuel predicts greater interest
and subsequent advances in Li-Fi.