Researchers make flexible electronics breakthrough

The developers claim the performance achieved by the tft was significantly higher than the performance of organic semiconductor and carbon nanotube transistors. Their tft had a high mobility of 35cm2/Vs and an on/off ratio of 6x106, compared to 1cm2/Vs and 104~105 in conventional solution based carbon nanotubes. While flexible thin film transistors have traditionally been produced using a variety of semiconductor materials such as silicon and zinc oxide, (which require vacuum deposition, high temperature curing and complex transfer processes), the team was able to simplify this process by continuously growing nanotubes in an atmospheric pressure chemical vapour deposition process. The nanotubes were then collected on the filter and transferred onto a polymer substrate using simple gas phase filtration and transfer processes. This enabled them to achieve clean, uniform carbon nanotube films in just a few seconds – meaning the process could be adaptable to high speed roll to roll manufacturing systems in the near future. The team then integrated the tfts on plastic substrates and achieved successful operations of ring oscillators and flip flops. High speed operations were achieved with a delay time of only 12microseconds per logic gate. According to researchers, the flip flops manufactured through these processes are the 'world's first' carbon nanotube based synchronous sequential logic circuits. The full research has been published in 6 February edition of the journal Nature Nanotechnology.