Polymer solar cells with higher efficiency levels created

Washington, November 27 : Solar cells that can be hanged like posters on a wall may soon be available in local hardware stores, thanks to researchers at the University of California, Los Angeles (UCLA) who have devised a way to synthesise a new plastic that has significantly greater sunlight absorption and conversion capabilities than previous materials.

Yang Yang, a professor of materials science and engineering at the university's Henry Samueli School of Engineering and Applied Science, says that the photovoltaic properties of the plastic can be dramatically improved by substituting a silicon atom for carbon atom in its backbone.

The researchers adds that this silole-containing polymer can also be crystalline, giving it great potential as an ingredient for high-efficiency solar cells. "With the reality of today's energy crisis, a new-game changing technology is required to make solar cells more popular. We hope that our newly synthesized polymer can eventually be used on solar cells far beyond their current rooftop applications. Imagine a house or car covered and powered by flexible solar films. Our dream is to see solar cells used everywhere," Yang said.

Polymers are low-cost plastics that are generally used in packaging materials, and inexpensive products like insulators, pipes, household products and toys.

Polymer solar cells utilize organic compounds to produce electricity from sunlight, are much cheaper to produce than traditional silicon-based solar cells, and are also environmentally friendly. However, their efficiency has been low to date.

Yang has revealed that the new polymer his created by his team first reached 5.1 percent efficiency, and improved to 5.6 percent in the lab in a few months.

He and his colleagues have shown that the photovoltaic material they use on their solar cells is one of the most efficient based on a single-layer, low-band-gap polymer. "Previously, the synthesizing process for the polymer was very complicated. We've been able to simplify the process and make it much easier to mass produce," said Jianhui Hou, UCLA postdoctoral researcher and co-author of the study.

"Though this is a milestone achievement, we will continue to work on improving the materials. Ideally we'd like to push the performance of the solar cell to higher than 10 percent efficiency. We know the potential is there," the researcher added. Hsiang-Yu Chen, a UCLA graduate student in engineering who is also a co-author on the study, said: "We hope that solar cells will one day be as thin as paper and can be attached to the surface of your choice. We'll also be able to create different colours to match different applications." The study has been published in the Journal of the American Chemical Society.

ANI