A new protective film developed by the researchers from the Indian Institute of Science may make organic semiconductor devices last significantly longer.
Organic semiconductors are tipped to be the technology of the future. They have many advantages over conventional semiconductor materials like silicon and germanium: they are flexible, lightweight, and easy to process. They can lead to novel applications like paper thin displays, wearable electronics, and highly efficient Organic Photo Voltaic Devices (OPVD). However, they are extremely sensitive to environmental factors like water vapour and oxygen.
“The basic idea of our work was to design polymer based barrier materials as blends, nanocomposites or with layered architectures those virtually can block water vapor. They can be used for encapsulating organic electronic devices” says Sindhu S, one of the members of the research team. Films made from such materials act as 'barriers' between the device and the external environment.
Glass is excellent as a material for encapsulation. However, since it is rigid, the flexibility offered by organic semiconductors cannot be used optimally. So, researchers have been looking out for materials that are flexible, but also as good as glass in keeping out water vapour and oxygen. They have realised that the answer lies in developing new “polymer based nanocomposites”.
Polymer films used for food packaging are good at blocking water vapor: a 1 m by 1 m sheet of such a material would allow just a couple of drops to seep in over an entire day. The new material developed by the IISc researchers is a few million times better than this, and it can increase the life of organic semiconductor devices by more than 20 times.
The new film which can be used for encapsulating organic semiconductor devices is actually made of many ultra thin layers of polymers and other materials. It consists of a layer of 'Nafion' in between bilayers of two different polymers, which together sit on 'Surlyn' substrate. Nafion and Surlyn are chemicals that are available commercially. The researchers tested this combination to encapsulate an organic semiconductor device, and found that the life of the device improved drastically.
About the research:
The work appeared in two papers, published in two different journals: Industrial and Engineering Chemistry Researcher and Langmuir.
Link to papers: dx.doi.org/10.1021/ie5036995, http://pubs.acs.org/doi/abs/10.1021/la503302f
Author information: Prof Giridhar Madras and Gayathri N Kopanati are at the Department of Chemical Engineering. Praveen C Ramamurthy is an Associate Professor at the Department of Materials Engineering, and also associated with the Center for Nanoscience and Engineering. Sindhu Seethamraju is at the Center for Nanoscience and Engineering.
Contact: Prof Giridhar Madras email@example.com, 91-80-22932321