A cool approach to flexible electronics

Jul 10, 2014
A cool approach to flexible electronics
Fully printed organic thin film transistors (OTFTs) on a paper substrate. (a) Schematic of the device structure for a fully printed OTFT on paper. (b) Arrays of fully printed OTFTs fabricated on a paper substrate inkjet printed with the NIMS logo before adding the device. (c) An optical microscope image of fully-printed OTFT arrays. (d) A magnified optical microscope image of the individual device. Arrays of fully printed organic thin film transistors fabricated on paper substrates that had the the NIMS logo ink jet printed on before processing.

A nanoparticle ink that can be used for printing electronics without high-temperature annealing presents a possible profitable approach for manufacturing flexible electronics.

Printing is considered to provide low-cost high performance flexible electronics that outperforms the amorphous silicon currently limiting developments in display technology. However the nanoparticle inks developed so far have required annealing, which limits them to substrates that can withstand high temperatures, ruling out a lot of the flexible plastics that could otherwise be used. Researchers at the National Institute for Materials Science and Okayama University in Japan have now developed a nanoparticle ink that can be used with printing procedures.

Developments in thin film transistors made from have provided wider, thinner displays with higher resolution and lower energy consumption. However further progress in this field is now limited by the low response to applied electric fields, that is, the low field-effect mobility. Oxide semiconductors such as InGaZnO (IGZO) offer better performance characteristics but require complicated fabrication procedures.

Nanoparticle inks should allow simple low-cost manufacture but the usually used are surrounded in non-conductive ligands – molecules that are introduced during synthesis for stabilizing the particles. These ligands must be removed by annealing to make the ink conducting. Takeo Minari, Masayuki Kanehara and colleagues found a way around this difficulty by developing nanoparticles surrounded by planar aromatic molecules that allow charge transfer.

The gold nanoparticles had a resistivity of around 9 x 10-6 Ω cm – similar to pure gold. The researchers used the nanoparticle ink to print organic thin film transistors on a flexible polymer and a paper substrate at room temperature, producing devices with mobilities of 7.9 and 2.5 cm2 V-1 s-1 for polymer and paper respectively – figures comparable to IGZO devices.

As the researchers conclude in their report of the work, "This room temperature printing process is a promising method as a core technology for future semiconductor devices."

Explore further: Formation of organic thin-film transistors through room-temperature printing

More information: Minari, T., Kanehara, Y., Liu, C., Sakamoto, K., Yasuda, T., Yaguchi, A., Tsukada, S., Kashizaki, K. and Kanehara, M. (2014), "Room-Temperature Printing of Organic Thin-Film Transistors with π-Junction Gold Nanoparticles." Adv. Funct. Mater.. doi: 10.1002/adfm.201400169

Related Stories

Recommended for you

Graphene and diamonds prove a slippery combination

May 25, 2015

Scientists at the U.S. Department of Energy's Argonne National Laboratory have found a way to use tiny diamonds and graphene to give friction the slip, creating a new material combination that demonstrates ...

Artificial muscles get graphene boost

May 22, 2015

Researchers in South Korea have developed an electrode consisting of a single-atom-thick layer of carbon to help make more durable artificial muscles.

How to make continuous rolls of graphene

May 21, 2015

Graphene is a material with a host of potential applications, including in flexible light sources, solar panels that could be integrated into windows, and membranes to desalinate and purify water. But all ...

Carbon nanothreads from compressed benzene

May 20, 2015

A new carbon nanomaterial – the thinnest possible one-dimensional thread that still retains a diamond-like structure – was created by the controlled, slow compression and decompression of benzene. The ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.