| Posted: August 10, 2010 |
Buried silver nanoparticles improve organic transistors |
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(Nanowerk News) Out of sight is not out of mind for a group of Hong Kong researchers who have demonstrated that burying a layer of silver nanoparticles improves the performance of their organic electronic devices without requiring complex processing.
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Their findings in a report published in the journal Applied Physics Letters ("Nonvolatile organic transistor-memory devices using various thicknesses of silver nanoparticle layers").
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A team led by Professors Paddy Chan and Dennis Leung of the Hong Kong Polytechnic University has shown that a simple layer of silver nanoparticles placed between two layers of the organic semiconductor pentacene improves performance just as much as painstakingly placing nanoparticles atop a tiny floating gate region.
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Because certain metal nanoparticles trap electric charges very effectively, they are becoming a popular additive for enhancing transistor performance and producing thinner transistors. Sandwiching a layer of nanoparticles is much more compatible with the low-cost, continuous roll-to-roll fabrication techniques used to make organic electronics than the more intricate patterning required to put material just in the transistor gate area.
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Moreover, Chan's group showed that the thickness of the nanoparticle layer changes the device performance in predictable ways that can be used to optimize transistor performance to meet application requirements.
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Transistors made with a 1-nanometer nanoparticle layer, for example, have stable memory that lasts only about three hours, which would be suitable for memory buffers. Transistors having a 5-nanometer-thick layer are more conventional and retain their charge for a much longer time.
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"We believe that organic memory has a very high potential for use in next-generation memory devices -- such as touchscreens and electronic paper -- where their flexibility and low-cost are most important," said Dr. Sumei Wang, a postdoctoral research fellow of the team.
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This work was supported by research grants from Hong Kong Polytechnic University and through funding from HKSAR (Hong Kong Special Administrative Region) through UGC (University Grants Committee).
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