Semitransparent organic solar cells could be used to transform regular
window glazing into a window that generates electrical power while
retaining its basic functionality.
GPEC, a developer of Organic Photovoltaic (OPV) technology for ultra-low
cost, high power solar cells, says this latest achievement is part of its
overall R&D efforts to increase the operating performance of its OPV
technology and develop insight into application areas. The company's
partner researchers detailed their work in the June 5, 2006 issue of
Applied Physics Letters.
Traditionally, PV or "solar" cells have been constructed of an inorganic
semiconductor like silicon. Efficient silicon-based devices, especially of
large surface area, are difficult and expensive to produce. Silicon cells
are fragile, heavy and opaque -- limiting applications and potential uses.
Cost is a critical factor in the solar cell industry as solar-generated
power is still four to six times more expensive to consumers than
coal-generated power, states the release.
Recent efforts have focused on the use of "organic" semiconductor
materials. Organic semiconductors contain the ubiquitous element Carbon
and have the potential to achieve ultra-low-cost production costs and high
power output in solar cells. Organic solar cells are ultra-thin, flexible
and can be applied to large areas including curved or spherical surfaces.
Because the organic layers are so thin, semitransparent solar cells can be
fabricated creating power-generating windows that retain a significant
portion of their basic transparency.
GPEC sponsored researchers at USC, Princeton and Michigan, led by
Professor Stephen R. Forrest at Michigan and Professor Mark E. Thompson at
USC, have focused on organic "small-molecule" devices that are assembled
literally a molecule at a time in highly efficient nanostructures.
Solar cells manufacturers typically use various techniques for trapping
incoming light inside the device so that power output can be improved. The
typical silicon solar cell is more than 200 microns thick and opaque to
visible light. Reflective back contacts are used in thinner thin-film
solar cells to increase the absorption of incoming light in the device.
Semitransparent cells, because they let some light pass through them, have
reduced power output.
In this recent work, GPEC partner researchers at USC, Princeton and
Michigan developed semitransparent organic solar cells that leverage the
superior absorption capabilities of organic semiconductor materials and
nanometer-scale films to achieve high levels of visible light transparency
while at the same time minimizing power loss.
"This demonstrates one of the exciting capabilities of organic solar
cells," said Aaron L. Wadell, Chief Operating Officer of Global Photonic
Energy Corporation. "Because of their strong absorption characteristics
and very thin layers, we can build windows that generate electricity while
retaining their basic functionality -- that is, they are still windows."