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New material to protect organic electronics from moisture

Protecting organic devices against water vapour is a concern for many scientists. Organic devices are known to be highly reactive to atmospheric water vapour, a significant cause for their premature degradation. A successful solution was generated by a team of four researchers at the Department of Chemical Engineering in IISc. Using a polymeric nanocomposite, they have devised an efficient and economical barrier to protect organic devices.

When a barrier of Magnesium Oxide (MgO) and Surlyn is used, it successfully wards off water vapour reaching the organic device for long periods of time, the researchers have found.

Many small molecules can be linked together to form long chains, known as polymers. Most devices today are built out of silicon, but organic devices are constructed using polymer materials. “The increasing demand for bendable and printable devices led to the development of organic electronics.  To imagine the future of electronics with flexibility in devices such as TVs and mobile phones, we need a protective moisture barrier layer, which we are concerned about”, says Gayathri N Kopanati, one of the members of the research team.

The polymers that organic materials consist of enable the easy transfer of electrons. But when they are exposed to the atmosphere, they react with oxygen and degrade, therefore restricting the transfer of elections and incapacitating them. To avoid this, the contact of organic materials with water vapour has to be minimized, or avoided altogether by constructing a barrier between both these elements.

One such barrier that can be used is glass. Unfortunately, glass, being rigid, renders the organic device inflexible. Since flexibility is one of the main advantages of these devices, using polymer based barriers instead of glass to prevent the entry of water vapour enables the device greatly. 

An innovative barrier design using polymer nanocomposites was developed by researchers at IISc. Polymer nanocomposites are a mixture of polymers and nanosized materials. In this case, the polymer used was Surlyn and Magnesium oxide (MgO) was the nanosized material.  MgO was combined and blended with Surlyn to create a film.

MgO is highly reactive to water vapour. When water comes into contact with MgO, it splits into its constituent molecules and forms Magnesium Hydroxide. When water vapour tries to pass through this barrier, it encounters resistance. “The barrier ensures that the water vapour will have to travel through a tortuous path, and so, will take longer to reach the other end”, explains Ms. Kopanati.  

This fabricated film has proved to be extremely efficient in minimizing the entry of water vapour in organic devices. Under very intense laboratory conditions (95% humidity), the efficiency of the fabricated film reduced by only 50% after 1 hour of continuous exposure to water vapour. “In normal, everyday conditions, the efficiency will be around 103 times higher”, adds Ms. Kopanati.

While organic devices are not yet fully commercialized, there are a few of these gadgets that have made it to the market. The primary aim of developing an effective barrier against water vapour for these devices is to increase their life span. The fact that MgO is immensely effective and inexpensive compared to other materials is a pleasing advantage. By adding barriers such as these to organic devices, we could see such flexible products in the market sooner than expected.

Author Information:

Dr. Giridhar Madras is a Professor in the Department of Chemical Engineering. Dr. Praveen C. Ramamurthy is an Assistant Professor in the Department of Materials Engineering. Sindhu Seethamraju is a PhD candidate at the Centre for Nanoscience and Engineering. Gayathri N Kopanati is pursuing her M.E. in Chemical Engineering at the Department of Chemical Engineering.

About the research:

This paper was published in RSC Advances on 31st March, 2015, and can be accessed at

http://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra03356j#!divAbs...

Contact: kgayathri.niveditha@gmail.com