Washington, Apr 30 : Protecting sensitive devices like solar cells from moisture will now be 1000 times more effective with the development of a new nanoengineered film by an Indian scientist that has the highest reported water vapour barrier performance to date.
This breakthrough technology-developed by Senthil Ramadas, at Singapore A STAR's Institute of Materials Research and Engineering (IMRE)-will open up new opportunities for the up-and-coming plastic electronics sector.
As the new films are 1,000 times more impervious to moisture than existing technologies, this indicates a longer lifetime for plastic electronic devices such as solar cells and flexible displays that use these high-end films but whose sensitive organic materials are easily degraded by water vapour and oxygen.
The performance of devices like organic light emitting diodes (OLEDs) and solar cells is sensitive to moisture because water and oxygen molecules seep through the protective plastic layer over time and degrades the organic materials which form the core of these products. Current commercially available films have a barrier property or water vapour transmission rate of about 10-3g/m2 per day, at 25C and 90percent relative humidity (RH).
Thin oxide barrier films usually have defects such as pinholes, cracks and grain boundaries, when fabricated onto plastic substrates. These defects cause a 'pore effect', where oxygen and water molecules are able to seep through and penetrate the plastic barrier.
These days, the barrier technologies focus on reducing these defects by using alternate organic and inorganic multi-layers coated on plastic. On the other hand, IMRE has taken an innovative approach to resolve the 'pore effect' by literally plugging the defects in the barrier oxide films using nanoparticles.
This reduces the number of barrier layers needed in the construction of the barrier film down to two layers in this unique nanoengineered barrier stack. IMRE's barrier stack consists of barrier oxide layers and nanoparticulate sealing layers. The nanoparticles used in the barrier film have a dual function - not only sealing the defects but also actively reacting with and retaining moisture and oxygen.
This results in a unique moisture barrier performance of better than 10-6g/m2/day, which exceeds the requirements for flexible organic device substrates. The barrier film also has a lag time of more than 2300 hours at 60 degree Celsius and 90 percent RH (i.e. the time required for moisture to pass through the barrier film under those conditions).
"With a level of protection that surpasses the ideal requirements for such films to date, manufacturers now have the opportunity to extend the lifetime of plastic electronic devices by leaps and bounds!," said Senthil Ramadas, principal investigator of the project.
Now, researchers are collaborating with various industry manufacturers for commercialization of the technology.
"The research team is already in talks with solar cells and flexible displays and lighting industry manufacturers who are currently evaluating the barrier films for product qualification", said Dr. Mark Auch, a member of the IMRE team.