Scientists from Korea and the United States said Friday (July 13) that they have created a highly efficient organic photovoltaic power cell that could trigger the widespread use of solar energy.
The team led by Lee Kwang-hee at the Gwangju Institute of Science and Technology (GIST) and Professor Alan Heeger of the University of California, Santa Barbara, said the solar cell they created has an energy efficiency rate of 6.5 percent.
"This is the highest number reached by any plastic-based organic photovoltaic solar cell that some scientists argued could not surpass the 5 percent mark," said Lee, a material science professor. The breakthrough has been published in the latest issue of Science magazine.
Energy efficiency indicates the percentage of sunshine that solar cells turn into electricity. Experts said an efficiency rate of 7 percent must be reached for plastic solar cells to become commercially viable.
The U.S. Department of Energy reached 5 percent in past tests, while energy efficiency figures attained by Japanese and European labs hover at around 3 to 4 percent.
Conventional inorganic silicon-based solar cells used in homes have an efficiency rate of 7 to 8 percent, while very expensive panels placed on satellites have numbers reaching 15 percent.
The scientist said high efficiency is attained by making better use of sunlight.
Plastic solar cells mimic natural photosynthesis found in plants by using fullerene and polymers to make electricity.
Existing photovoltaic panels, however, only used the luminous part of solar rays.
"In comparison, the jointly developed cells can extract power from infrared sources as well as luminous rays that enhance efficiency," he said.
He said this was possible because South Korean scientists have perfected the use of titanium oxide to make tandem layered solar cells. The upper layer absorbs luminous light, while the lower part makes use of the infrared rays.
Lee also said that through a high-tech encapsulation process, the life span of the plastic-based organic photovoltaic solar cell could be extended considerably.
Previously organic photovoltaic panels reported a noticeable drop in efficiency over time.
Other advantages of the new solar cells are low manufacturing costs, simplified production using a spin coating method, and the thinness of the finished product that can be made flexible.
"Conventional solar cells cost US$2.3 to generate one watt of electricity compared to $0.1 for the latest plastic cells," he said.
The scientist said if the technology is perfected the new panels could grab a large percentage of the global solar energy market that is expected to reach $34 billion in 2010, and hit $100 billion in 2050.
Lee, who made headlines last year by unveiling plastic-based polymer that can conduct electricity, said merging of the two technologies could open new horizons.
He said mixing the two could allow solar cells to be placed over windows and roofs, and allow mobile phones and electronic appliances to be recharged using solar energy.