Thin, Flexible Solar Panels Revealed

Today’s solar panels are heavy, inefficient, and expensive. Tomorrow’s solar panels, according to Nobel Prize laureate and UCSB chemistry professor Dr. Alan Heeger, will be lightweight, economical, and affordable.

On Friday, February 20, Heeger spoke to more than 100 people at the First Presbyterian Church about recent breakthroughs and advances in the emerging field of “Low Cost ‘Plastic’ Solar Cells.” A new generation of thin, flexible solar panel is in the works, he explained, that will eliminate many of the problems associated with traditional solar materials.

Heeger, who could not be reached for interview, began his talk by describing the pressing need for the development and implementation of renewable sources of energy in response to increasing climate change and looming global warming. In succinct and understandable terms, he explained that simply reducing the world’s need for energy is not a realistic or feasible goal – people in developed countries, Heeger argued, simply will not accept a reduction in a standard of living, and people in developing countries will not give up their “dream of a better life.” Heeger used the term “energy justice” to describe and encapsulate the world population’s mindset that prevents an overall decrease in energy consumption.

So, if lessening the energy need is not an option, where does that leave us?

While nuclear and wind power are certainly practical opportunities, Heeger asserted, these forms of energy possess their own drawbacks: There are obvious dangers associated with fissionable material and the common response to the installation of wind turbines and generators is “not in my backyard.” That, said Heeger, leaves solar power. “The amount of energy that comes from the sun in one hour is enough to power the entire Earth for one year. We need to determine how to better harness and make use of this energy.”

One of the first steps in recognizing the potential for solar energy, Heeger argued, is allowing the technology and hardware to be more affordable and attainable for the average homeowner. As of now, traditional silicon solar panels are wildly expensive due to their high production costs. It takes a significant amount of time for a solar panel to produce enough electricity to pay for itself. This is the reason so few residential buildings are able to support such equipment. The new solar panels described in Heeger’s talk are significantly cheaper as they are literally rolled off a production line and are much less material and labor intensive.

The technology behind the new panels builds off a previous discovery made in 1992 that determined polymers (plastics) were able to absorb photons (sunlight) and, with a little electrical engineering, conduct an electric current. Heeger, who has pioneered research in the area of semiconducting and metallic polymers, explained that he and his colleagues used this jumping off point to develop a specific polymer that would be able to more effectively absorb sunlight than the silicon used today. That new polymer, when combined with a solution (essentially an “ink” with electronic functionality) spontaneously creates an electronic circuit on a microscopic scale. Heeger put this process in scientific terms as “self assembly of bulk heterjunction nanomaterials by spontaneous separation.” This solution, Heeger went on, is then applied and solidified to an adhesive medium to give it a two-dimensional form and structure.

Once this process was invented, the key was finding an economical way of producing mass quantities of this new photon absorbent material. Heeger’s company, Konarka, soon acquired the roll-to-roll printing machines previously used by Polaroid in Massachusetts to literally print the solution onto sheets of medium. The machines, Heeger said, “could not have been better designed for our purposes.” Heeger and Konarka are continuing to perfect their newly developed production line, and their first products are slated for release and distribution by 2010 after years of rigorous longevity and durability testing.

The sample panel Heeger presented to the audience flexed and moved in his hands, and it was, as promised, as thin as a sheet of paper. He pointed out the readout mechanism and explained that, in addition to increasing absorption efficiency to 10-15 percent, the panel is also able to absorb reflected and diffused light because of its elastic property. The commercial applications, he went on, are seemingly endless. The panels can be incorporated into umbrellas, awnings, tents, etc. They can be rolled up and moved easily or simply laid on a roof permanently. He also spoke of the possibility of one day incorporating the solar polymer solution into actual roof tiles or, instead of tinting windows with opaque plastic, putting solar panels within windows to both block and absorb sunlight. Heeger also briefly touched on the possibility of an eventual “spray-on” panel that could be applied to large surface areas.

While many of these possibilities are still years away from development, Heeger assured the audience that the technology exists and that the challenge is engineering products around it. He also explained that many steps still must be taken before solar energy becomes a truly viable alternative. For instance, even the new solar panels are still quite inefficient at harnessing voltage, according to Heeger, and a new semiconducting polymer needs to be developed to solve this issue. This, he explained, will minimize the energy gap for harvesting sunlight. Also, the molecular structure of the polymers needs to be better matched to the sun’s energy emissions in order to increase productivity. Heeger’s attitude, even in light of the vast amount of work to come, remains optimistic.