Scientists have spent decades trying to build flexible plastic solar cells efficient enough to compete with conventional cells made of silicon. To boost performance, research groups have tried creating new plastic materials that enhance the flow of electricity through the solar cell. Several groups expected to achieve good results by redesigning pliant polymers of plastic into orderly, silicon-like crystals, but the flow of electricity did not improve.
Recently, scientists discovered that disorder at the molecular level actually improves the polymers’ performance. Now Stanford University researchers have an explanation for this surprising result. Their findings, published in the Aug. 4 online edition of the journal Nature Materials, could speed up the development of low-cost, commercially available plastic solar cells.
“People used to think that if you made the polymers more like silicon they would perform better,” said study co-author Alberto Salleo, an associate professor of materials science and engineering at Stanford. “But we found that polymers don’t naturally form nice, well-ordered crystals. They form small, disordered ones, and that’s perfectly fine.”
Instead of trying to mimic the rigid structure of silicon, Salleo and his colleagues recommend that scientists learn to cope with the inherently disordered nature of plastics.
In the study, the Stanford team focused on a class of organic materials known as conjugated or semiconducting polymers – chains of carbon atoms that have the properties of plastic, and the ability to absorb sunlight and conduct electricity.
Read more at: Phys.org