Superhydrophobic films to protect solar cells

Materials World magazine
1 Jul 2008

A water barrier film that is reportedly 1,000 times more effective than other technologies on the market has been developed by researchers at the Institute of Materials Reseach and Engineering (IMRE) in Singapore. This could help protect sensitive devices like organic light emitting diodes and solar cells from moisture damage.

The Singapore sealing method uses metal nanoparticles suspended in a monomer solvent and applied to an aluminium oxide film (researchers could not reveal the exact composition of the sealing materials). ‘The metal particles are freely moving in the film, so they migrate towards any pinholes, plugging the gaps,’ explains Dr Mark Auch of the IMRE. This contrasts to traditional barrier techniques, which stagger five to 10 organic andinorganic film layers onto the surface, creating a zig-zag pattern that is difficult for water to move through, but is prone to cracking.

The metal particles in the new film are able to react with and retain moisture and oxygen molecules, preventing them from entering the device. ‘The metallic particles react with oxygen and become metal oxide. The metal oxide can then react with water and become metal hydroxide,’ says Auch. ‘The nanoparticles increase the surface area, therefore trapping a sufficient amount of water and oxygen.’

The resulting moisture barrier performance is between 10-3g to 10-5g/m2/day, or one millionth of a gram per square metre per day.

The IMRE has signed a collaborative agreement with G24Innovations, a solar cell manufacturer based in Cardiff, UK, to supply it with film rolls from July onwards, and is hoping to get the results of these commercial trials by September.