A team led by Professors Paddy Chan and Dennis Leung, Hong Kong Polytechnic University, China, has demonstrated that the memory effect in organic memory devices can be modified by adjusting the thickness of a silver nanoparticle (NP) layer embedded within the pentacene semiconductor.

Transistors with a 1 nm layer are shown to have stable memory that lasts about three hours, which would be suitable for memory buffers. Transistors with a 5 nm-thick layer are more conventional and retain their charge for a longer time.

By layering the NPs rather than placing them atop a floating gate region, manufacture becomes compatible with the low-cost, continuous roll-to-roll fabrication techniques while similar results are achieved compared to the more complicated technique.

“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.

• Nonvolatile organic transistor-memory devices using various thicknesses of silver nanoparticle layers
  S. M. Wang, C. W. Leung, P. K. L. Chan,
  Appl. Phys. Lett. 2010, 97, 023511.
  DOI: 10.1063/1.3462949