Researchers at Ohio State University, led by professor Paul Berger, are experimenting with polymer semiconductors that absorb the sun’s energy and generate electricity - with the goal of lighter, cheaper, and more-flexible solar cells. The team has discovered that adding tiny bits of silver to the plastic boosts the material's electrical current generation.
Berger, professor of Electrical and Computer Engineering and Physics, and his team measured the amount of light absorbed and the current density - the amount of electrical current generated per square centimeter - generated by an experimental solar cell polymer with and without silver nano-particles.
Without silver, the material generated 6.2 milli-amps per square centimeter. With silver, it generated 7.0 - an increase of almost 12 percent.
The small silver particles help the polymer capture a wider range of wavelengths of sunlight than would normally be possible, which in turn increases the current output, Berger explained. With further work, this technology could go a long way toward making polymer solar cells commercially viable.
“The light absorption of polymer solar cells is inadequate today,” Berger said. “The top-performing materials have an overall efficiency of about 5 percent. Even with the relatively low production cost of polymers compared to other solar cell materials, you’d still have to boost that efficiency to at least 10 percent to turn a profit. One way to do that would be to expand the range of wavelengths that they absorb. Current polymers only absorb a small portion of the incident sunlight.”