Plastic Solar Cells Get Needed Jolt

Scientists show a new plastic solar cell developed by a team of South Korean and U.S. scientists. / Korea Times

By Kim Tong-hyung
Staff Reporter

Scientists have engineered an approach they claim will lead to improved solar cells with power-conversion efficiencies of more than 6 percent, according to the South Korean and U.S. researchers behind the discovery.

Lee Kwang-hee, a professor of materials science at the Gwangju Institute of Science and Technology (GIST), claimed that the recent study, published in peer-review journal Nature Photonics, marks an advancement in efforts to make plastic cells commercially viable.

Developing inexpensive, mass-produced plastic solar cells has been a major goal in recent technology. They're made mainly of organic molecules and may easily be bent or wrapped around surfaces, making them suitable for use in a wider range of products.

Scientists and engineers believe that plastic solar cells will eventually become less expensive alternatives to traditional solar cells, usually made from silicon, which is inflexible and comparatively heavy, as the large-scale production of organic polymers would be significantly less expensive than the current costs for fabricating silicon.

However, plastic cells lag behind silicon in terms of power output. For the former to be commercially viable, they must reach a level where they convert at least some 8 percent of solar energy into electricity, experts say, and that still wouldn't compete with the maximum 40 percent achieved by conventional cells.

Nonetheless, the 6.2-percent efficiency achieved by Lee and his colleagues, including Nobel Prize-winning chemist Alan Heeger of the University of California, Santa Barbara, represents the highest mark ever for a non-tandem single solar cell.

Lee and Heeger also collaborated on a 2007 study published in Science, which reported the creation of a tandem plastic cell stacking multiple polymer layers for wider use of the solar spectrum, achieving a power-conversion rate of 6.5 percent.

Previously, even the best plastic cells struggled to reach over 5 percent in efficiency when tested singularly, Lee said.

``When under green light, the new plastic cell achieved 17.2-percent efficiency. By combining new materials that absorb light better and have higher open circuit voltage with titanium-suboxide, we were able to get more energy from the charged electrons within the layers,'' Lee said.

``Considering that plastic cells could be bent and folded and are cheaper to produce, commercial potential is enormous. They can be used for portable recharging devices and on glass, roof tiles, parasols and probably even clothing.''

thkim@koreatimes.co.kr

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