BILBAO, SPAIN- Scientists and industries interested in exploring and exploiting the unique properties of graphene gathered last week at the ImagineNano Graphene 2013 conference in Bilbao, Spain. The timing of the meeting was perfect as it came only a few months after the European Commission announced a billion euros of funding for the Graphene Flagship.
With this financial support for research and development, graphene-based technologies and associated business opportunities have never been so promising. Although, the question on the lips of all participants of Graphene 2013 is: will graphene deliver the goods?
Many of the industrial speakers tried to answer this billion dollar question by presenting their vision and roadmap for the graphene market. According to Kitty Cha, research chemist at BASF, graphene commercialization will start with composite materials and electronic inks. For such applications, graphene can be extracted from graphite flakes, which greatly simplifies its large scale production.
In the mid-term, many believe that technologies based on large graphene films such as displays, photovoltaic cells, batteries or super-capacitors will emerge. Amaia Zurutuza, scientific director of Graphenea, illustrated the potential of graphene for the energy industry by presenting her collaborative research on batteries and light harvesting.
However, opinions differ when it comes to the long-term applications. Graphene-based transistors are mentioned often, but according to Tomas Palacios, associate professor of electrical engineering at MIT, it will be difficult to compete against the silicon industry: “the economics are against us, the work of thousands of intelligent silicon engineers is against us, and the physics is against us”.
Much ink has been spilt on the outstanding physical properties of graphene, but the technological importance might have been exaggerated in some cases. Palacios, for example, argued that the electronic mobility of a material is not a relevant property for today’s transistor.
In the same way, Seongjun Park from Samsung electronics baffled the audience during his talk when he revealed that thin ITO films were flexible just like graphene, thus contradicting the common idea that only graphene is capable of making flexible displays.
In fact, Palacio suggested that in order to be technologically promising, a given property of graphene should be at least ten times better than that of the material dominating the market. This “reality check” illustrates how difficult it is for graphene to compete against other materials, such as silicon, in their own domain.
All graphene developers agree: If graphene does not replace current technologies, it will lead to novel technological concepts and devices.
To support this idea, Palacios invoked Kroemer’s “Lemma of New Technology”: “The principal applications of any sufficiently new and innovative technology have always been- and will continue to be – applications created by that technology”.
For this technological shift to happen, engineers will have to focus on the truly unique properties of graphene. One of which is its electrical ambipolarity, according to Palacios, who showed it could be used for nonlinear electronics, chemical sensors and IR photodetectors. Park proposed that graphene be employed as a metal with a tuneable work function, which could help reduce the contact resistances present in current silicon devices. As well, Max Lemme, professor at the University of Siegen, presented a graphene hot-electron transistor which takes advantage of the extreme thinness of graphene.
All these new technologies hold great promise but many believe that the best is yet to come. For that, “we need a good idea!”, concluded Park.
In fact, graphene might just be the tip iceberg. The “good idea” that graphene developers are hunting for might include, not only graphene, but a whole class of 2D crystals like boron nitride and transition metal dichalcogenides.
According to Antonio Castro Neto, director of the Graphene Research Center of Singapore, graphene is just one example of a 2D crystal, and we must go beyond it. This was echoed by Jiwoong Park, associate professor at Cornell University, who stated that “the whole field of graphene is moving beyond graphene now”.
“Beyond graphene” was definitely one of the leitmotivs of the conference. Even Jari Kinaret, director of the graphene flagship, was compelled to specify that the word “graphene”, in the context of the flagship, includes all 2D crystals.
Assembling these various 2D crystal in heterogeneous stacks allows scientists to create 3D materials that do not exist in nature and to tailor their properties. In other words, one plus one equals more than two: combining the great properties of graphene with those of other 2D crystals gives rise to multi-functional, high performance 3D materials.
One must agree that we live in “the most exciting time in history for electronics”, as concluded by Palacios.