The main drawback to solar photovoltaic energy is the large cost of raw materials. Even when using cost-reduction strategies like NREL’s room temperature, room pressure bath, to reduce reflectivity and provide more chambers for the photons to “work” in, costs still remain high.
Add production costs to material costs, with solar cell manufacturing plants costing upward of $1 million, and thin-film twice as expensive, and you have a threshold beyond which solar energy can’t seem to find its way, at least in terms of today’s consumer, who faces the dual challenges of inflation (in food, fuel and clothing costs) and recession in terms of the dollar’s purchasing value.
Researchers at Winston-Salem, North Carolina-based Wake Forest University have developed a new solar technology which could double the energy production of flat solar cells at a fraction of the cost, because the material required to make them is nearly as ubiquitous as dust.
This material is plastic, according to Director of Nanotechnology and Molecular Materials Center David Carroll, Ph.D., and its use – as organic or flexible plastic solar cells (fiber-based solar cells) – can make a huge difference both in terms of solar efficiency and cost. Currently, the university holds a European patent; a U.S. patent is pending.
The technology, which involves millions of microscopic plastic fibers, called “nanofilaments”, is based on the same function as the veins in tree leaves that allow for greater photosynthesis. The technique, called biomimicry, allows solar panels to be made that are flexible yet durable, and conformable enough to be wrapped or shaped around structures, or even spray-painted onto surfaces.
Each plastic solar cell consists of a straw-shaped optical inner core made with glass, poly(methyl methacrylate; PMMA, a shatterproof plastic), or perfluorocyclobutane (PFCB, an ether polymer coating); surrounded by a layer of ITO:PEDOT (indium, tin oxide on top of a polymer mix of two ionomers); followed by a light-absorbing layer, with an external reflector/contact made of lithium fluoride and aluminum. Some proprietary components are also included.
The plastic solar cell technology will be licensed to solar startup FiberCell Inc., located in the Piedmont Triad Research corridor near Winston-Salem, Greensboro and High Point. FiberCell, which is still in development at the commercial level, will eventually leverage its partnerships in the thin-film and coatings industries to bring the product to market, potentially revolutionizing the BIPV (building integrated photovoltaics) field.
Because the cells can collect sunlight at many angles, and thus across the entire spectrum of light, the efficiency is greater. This efficiency is further enhanced by the ability of the light “straws” to capture photons, which bounce back and forth like the balls in a pinball machine, up and down the length of the cells, until most of their energy is dissipated.
