These visibly transparent polymer solar cells were produced using solution processing. |
UCLA
researchers have developed a new transparent solar cell that is an
advance toward giving windows in homes and other buildings the ability
to generate electricity while still allowing people to see outside.
Their study appears in the journal ACS Nano.
The
UCLA team describes a new kind of polymer solar cell (PSC) that
produces energy by absorbing mainly infrared light, not visible light,
making the cells nearly 70% transparent to the human eye. They made the
device from a photoactive plastic that converts infrared light into an
electrical current.
“These
results open the potential for visibly transparent polymer solar cells
as add-on components of portable electronics, smart windows and
building-integrated photovoltaics and in other applications,” said study
leader Yang Yang, a UCLA professor of materials science and
engineering, who also is director of the Nano Renewable Energy Center at
California NanoSystems Institute (CNSI).
Yang
added that there has been intense world-wide interest in so-called
polymer solar cells. “Our new PSCs are made from plastic-like materials
and are lightweight and flexible,” he said. “More importantly, they can
be produced in high volume at low cost.”
Polymer
solar cells have attracted great attention due to their advantages over
competing solar cell technologies. Scientists have also been intensely
investigating PSCs for their potential in making unique advances for
broader applications. Several such applications would be enabled by
high-performance visibly transparent photovoltaic (PV) devices,
including building-integrated photovoltaics and integrated PV chargers
for portable electronics.
Previously,
many attempts have been made toward demonstrating visibly transparent
or semitransparent PSCs. However, these demonstrations often result in
low visible light transparency and/or low device efficiency because
suitable polymeric PV materials and efficient transparent conductors
were not well deployed in device design and fabrication.
A
team of UCLA researchers from the California NanoSystems Institute, the
UCLA Henry Samueli School of Engineering and Applied Science and UCLA’s
Department of Chemistry and Biochemistry have demonstrated
high-performance, solution-processed, visibly transparent polymer solar
cells through the incorporation of near-infrared light-sensitive polymer
and using silver nanowire composite films as the top transparent
electrode. The near-infrared photoactive polymer absorbs more
near-infrared light but is less sensitive to visible light, balancing
solar cell performance and transparency in the visible wavelength
region.
Another
breakthrough is the transparent conductor made of a mixture of silver
nanowire and titanium dioxide nanoparticles, which was able to replace
the opaque metal electrode used in the past. This composite electrode
also allows the solar cells to be fabricated economically by solution
processing. With this combination, 4% power-conversion efficiency for
solution-processed and visibly transparent polymer solar cells has been
achieved.
“We
are excited by this new invention on transparent solar cells, which
applied our recent advances in transparent conducting windows (also published in ACS Nano) to fabricate these devices,” said Paul S.Weiss, CNSI director and Fred Kavli Chair in NanoSystems Sciences.
Study
authors also include Weiss; materials science and engineering
postdoctoral researcher Rui Zhu; Ph.D. candidates Chun-Chao Chen, Letian
Dou, Choong-Heui Chung, Tze-Bin Song and Steve Hawks; Gang Li, who is
former vice president of engineering for Solarmer Energy, Inc., a
startup from UCLA; and CNSI postdoctoral researcher Yue Bing Zheng.
Visibly Transparent Polymer Solar Cells Produced by Solution Processing
