慢速英语:Paintable Solar Cells May Replace Silicon-Based Devices

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Solar panels are manufactured in factories. Some of the devices are made with cadmium chloride, a substance shown to be harmful to human health. But an American researcher says manufacturers soon may be able to create solar panels with safe, non-toxic solutions.

Solar cell technology currently depends on costly photovoltaic materials, such as silicon and cadmium telluride. Photovoltaic materials have the ability to take in photons from sunlight and release electrons. When these free electrons are captured, an electric current results. This current can be used as electricity.

Thanks to photovoltaic materials, solar cell technology is expanding. But the cost of producing and using solar cells remains high.

Troy Townsend has developed solar cell technology with less costly materials. But he adds that the technology is also less effective than the existing technology.

Mr. Townsend is an assistant professor at Saint Mary’s College in Maryland. He says that silicon solar cells are usually between 16 and 18 percent efficient. The solar cells he and other researchers have developed are between 5 and 12 percent efficient. But, he adds that the cells they developed could be painted or sprayed to make a device fully solution-processed.

This less costly material may be used to cover large surfaces, like housetops of a community. The photovoltaic material is produced by mixing nanocrystals, very small particles, with chemical compounds.

"All of these layers we have been able to produce as an ink. They can be printed, sprayed or spin-coated to make an entire device fully solution-processed."

When placed on a surface, like a piece of glass, the ink layers have to be heated with another agent or substance. Troy Townsend discovered that this can be done with non-toxic salts instead of harmful substances.

Individual cells can be connected to build up electric current or voltage.

Mr. Townsend hopes that someday solar panel systems may become much more cost-friendly for individual users.

"The goal of this is to be able to put this in the hands of an average everyday person. They have all the tools they need to build these devices in their home kitchen,” he says.

He hopes that more research will lead to the increased efficiency of paintable solar cells.

I’m Jonathan Evans.

VOA’s George Putic reported this story from Washington. Jonathan Evans adapted it for Learning English. George Grow was the editor.