New generation of flexible graphene transistors

March 15, 2012
Single-layer graphene in solution used for making flexible transistors on a polyimide substrate (a sheet of thermostable polymer). Credit: CEA

Making electronic components using graphene, a material composed of a single layer of carbon atoms, is one of today's major technological challenges. Researchers hope to harness the outstanding electron mobility of graphene and also use the material to design low-cost, flexible electronics. Research teams from CEA, CNRS, Université de Lille 1 and Northwestern University have come up with a novel process for manufacturing transistors that combine flexibility and electron mobility and are capable of working at very high frequencies in the GHz range. The process uses a form of graphene in solution that is compatible with printing techniques. Electronic components such as these should lead to the development of high-performance electronic circuits built into everyday objects.

The results appeared in the journal Nano Letters on March 14, 2012.

, a material that consists of a single layer of hexagonal , has some outstanding properties. In particular, its high is expected to help electronic components perform at very high frequencies. Its mechanical properties also make it flexible. These two properties – electron mobility and flexibility – could be usefully employed to make electronic components and circuits for various applications, such as developing flexible screens and very high-performance and at low cost.

Several methods of graphene synthesis are currently available. One of them involves producing graphene as a solution of tiny particles, a few hundred nanometers in diameter, which are stabilized in water by surfactants. The method of synthesis used to obtain the resulting “conductive ink” makes it possible to select only single-layer sheets that exhibit remarkable electronic properties (instead of a combination of single-layer and multilayer graphene). Another specific feature is that components can be produced on a very wide range of media, including glass, paper or organic substrates.

The research teams from CEA, CNRS, Université de Lille 1 and Northwestern University developed the first ever process for making flexible transistors from solubilized graphene on polyimide (a thermostable polymer) substrates. They then made an in-depth study of high-frequency performance of these transistors.

In the process developed by the researchers, sheets of graphene in solution are deposited on the substrate with an alternating electric field applied between electrodes made in advance. This technique, known as dielectrophoresis or DEP, is used to guide the graphene deposition process so as to obtain a high density of deposited sheets in certain spots. This density is essential for achieving outstanding high-frequency performance. The charge mobility in the transistors is in the region of 100 cm2/V.s, a far higher value than that obtained with semiconductor molecules or polymers. These transistors thus achieve very high frequencies – around 8 GHz – a level of performance never before obtained in organic electronics!

The results show that “conductive ink” graphene is a highly competitive material for making flexible electronic applications in a high-frequency range (GHz) that is completely out of reach for conventional organic semiconductors. This new generation of transistors offers excellent prospects for many applications, including flexible screens (folding or roll-up), electronic devices built into fabrics or other everyday objects, such as RFID tags, capable of processing and transmitting information.

Explore further: IBM introduces new graphene transistor

More information: Flexible Gigahertz Transistors Derived from Solution-Based Single-Layer Graphene. Cedric Sire, et al., Nano Letters, Mar 14, 2012.

Related Stories

IBM introduces new graphene transistor

April 11, 2011

( -- In a report published in Nature, Yu-ming Lin and Phaedon Avoris, IBM researchers, have announced the development of a new graphene transistor which is smaller and faster than the one they introduced in February ...

Two graphene layers may be better than one

April 27, 2011

( -- Researchers at the National Institute of Standards and Technology have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results reveal that not ...

Graphene applications in electronics and photonics

November 2, 2011

Graphene, which is composed of a one-atom-thick layer of carbon atoms in a honeycomb-like lattice (like atomic-scale chicken wire), is the world's thinnest material – and one of the hardest and strongest. Indeed, the ...

Motorized roller could mass-produce graphene-based devices

February 23, 2012

( -- Finding a simple, scalable way to pattern graphene for future electronics applications is one of the biggest challenges facing graphene researchers. While lithography has been widely used to create graphene ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...

Mathematicians identify limits to heat flow at the nanoscale

November 24, 2015

How much heat can two bodies exchange without touching? For over a century, scientists have been able to answer this question for virtually any pair of objects in the macroscopic world, from the rate at which a campfire can ...

New sensor sends electronic signal when estrogen is detected

November 24, 2015

Estrogen is a tiny molecule, but it can have big effects on humans and other animals. Estrogen is one of the main hormones that regulates the female reproductive system - it can be monitored to track human fertility and is ...


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.