European polymer project develops flexible solar-powered battery

23 April 2007 – An EU research project has developed a thin polymer solar battery flexible enough for use in flat but bendable electronic objects such as smart cards and curved mobile phones.

The EURO-PSB project has created a prototype battery weighing just two grams and less than one millimetre thick, producing 0.6 volts in charge, which can be increased by adding extra strips to a cell.

Able to draw on artificial and natural light, the battery “is always charged with the optimum voltage, independently of the light intensity”, said an EU report. It said the battery has been designed for people whose “mobile phone is their lifeline” and who “know how frustrating it feels when the phone's battery runs out of juice and has to be recharged.” However, artificial light, such as office light, could be too weak to generate enough power for mobile phones.

One of the project's participants, the Swiss State Secretariat for Education and Research, said the battery involved the development of a “thin (less than 1 mm) and flexible solar battery by coupling on top of each other a polymer photovoltaic cell with a lithium-polymer battery.”

One problem for the researchers, was sustaining the cells’ life because they are vulnerable to photo-degradation after a few hours of air exposure. As a result, they encapsulated them inside a flexible gas barrier, extending their life to about 3,000 hours. The EU report said production was cost effective, “since they can be printed on a roll-to-roll machine at low temperatures.”