New technology boon for low-cost polymer solar cells

A team of chemists has set a new world record for fullerene-free polymer solar cells by developing a unique combination of a polymer.

With this technology, the sun's energy is converted with an efficiency of 11 percent -- a value that strikes most solar cells with fullerenes and all without fullerenes, said the scientists from Linköping University in Sweden and the Chinese Academy of Sciences (CAS).

A fullerene is a molecule of carbon in the form of a hollow sphere, ellipsoid, tube, and many other shapes.

The new work, led by professor Jianhui Hou at the CAS, can lead to avoiding costly and unstable fullerenes in the near future.

"We have demonstrated that it is possible to achieve a high efficiency without using fullerene. Such solar cells are also highly stable to heat. Because solar cells are working under constant solar radiation, good thermal stability is very important," explained Feng Gao, physicist at Linköping University.

Polymer solar cells have in recent years emerged as a low-cost alternative to silicon solar cells.

In order to obtain high efficiency, fullerenes are usually required in polymer solar cells to separate charge carriers.

However, fullerenes are unstable under illumination, and form large crystals at high temperatures.

"The combination of high efficiency and good thermal stability suggest that polymer solar cells now come a step closer to commercialisation," Gao added.

The team will present their findings in the journal Advanced Materials.