New plastic solar cell unveiled

Plastic cells cost only a fraction of the more common silicon cells used in solar-powered products, such as calculators. But plastic cells typically are fragile and last only for a few days.

“Our new cell has a life span of 2½ years, which must be a world record for plastic cells,� said Frederik Krebs, senior scientist with the state-owned Risoe national laboratory.

Some experts not affiliated with the project said the plastic cells would need to become more efficient before they could be used for consumer products.

The Danish scientists said they were using more stable form of plastic as the active substance in the cell, which converts energy from the sun's rays into electricity.

The market price for a silicon cell is up to $800 (U.S.) per square metre, while a plastic cell of the same size costs less than $15, they said.

Plastic cells, however, have relatively low efficiency – they exploit only 0.2 per cent to 5 per cent of the sun's energy, compared with 12 per cent to 15 per cent for silicon cells.

“We have focused on durability and succeeded; now we will make it more efficient,� Mr. Krebs said.

Silicon cells are widely used in items such as calculators and watches, and some houses get all their energy supply from silicon solar cells. There are also solar-powered cars, but they are extremely expensive and therefore not mass-produced.

“There's a huge demand for solar cells, and the silicon-cell producers can't meet the strong demand. With the new increased durability, plastic solar cells should soon be competitive and appear on the market,� Mr. Krebs said. “People could for example have a strip of plastic solar cells on their mobile phones instead of a battery.�

Tom Markvart, head scientist at the solar research group at the University of Southampton called the new research “a major development� but emphasized there were still many hurdles before plastic solar cells would become available on the market.

“Plastic cells still need to become more stable and have better efficiency,� he said. “And maybe the answer to the solar cell of the future is a combination of silicon and plastic, where you exploit the best of the two worlds.�

The research will be presented at a solar cell convention in San Diego next month.