The MIT team has
achieved the thinnest and lightest complete solar cells ever made,
they say. To
demonstrate just how thin and lightweight the cells are, the researchers
draped a working
cell on top of a soap bubble, without popping the bubble.
Photo: Joel Jean
and Anna Osherov
(February 26, 2016) Ultrathin,
flexible photovoltaic cells from MIT research could find many new uses.
Imagine solar cells so thin, flexible, and lightweight that
they could be placed on almost any material or surface, including your hat,
shirt, or smartphone, or even on a sheet of paper or a helium balloon.
Researchers at MIT have now demonstrated just such a
technology: the thinnest, lightest solar cells ever produced. Though it may
take years to develop into a commercial product, the laboratory
proof-of-concept shows a new approach to making solar cells that could help
power the next generation of portable electronic devices.
The new process is described in a paper by MIT professor
Vladimir Bulović, research scientist Annie Wang, and doctoral student Joel
Jean, in the journal Organic Electronics.
Bulović, MIT’s associate dean for innovation and the
Fariborz Maseeh (1990) Professor of Emerging Technology, says the key to the
new approach is to make the solar cell, the substrate that supports it, and a
protective overcoating to shield it from the environment, all in one process.
The substrate is made in place and never needs to be handled, cleaned, or
removed from the vacuum during fabrication, thus minimizing exposure to dust or
other contaminants that could degrade the cell’s performance.
“It could be so
light that you don’t even know it’s there, on your shirt or on your notebook,”
Vladimir Bulović
says. “These cells could simply be an add-on to existing structures.”
Photo: Joel Jean
and Anna Osherov
“The innovative step is the realization that you can grow
the substrate at the same time as you grow the device,” Bulović says.
In this initial proof-of-concept experiment, the team used a
common flexible polymer called parylene as both the substrate and the
overcoating, and an organic material called DBP as the primary light-absorbing
layer. Parylene is a commercially available plastic coating used widely to
protect implanted biomedical devices and printed circuit boards from
environmental damage. The entire process takes place in a vacuum chamber at
room temperature and without the use of any solvents, unlike conventional
solar-cell manufacturing, which requires high temperatures and harsh chemicals.
In this case, both the substrate and the solar cell are “grown” using
established vapor deposition techniques.