Transparent organic electronics based on graphene

Transparent organic electronic and optoelectronic devices are nowadays emerging technologies for future applications, for example in smart windows and in photovoltaic cells. The attributes of organic materials include large and ultrafast nonlinear optical responses and large colour tuneability. However, the electrical conductivity of organic materials is usually poor and this limits their utility. Here we propose to pursue a new type of organic material for such applications, a material that has a high electrical conductivity and thus has the potential to revolutionise the field: the material is graphene. This is a sheet of carbon just one atom thick, with spectacular strength, flexibility, transparency, and electrical conductivity. The proposed project is directed specifically at tuning the electronic properties of graphene in order to allow the potential of this material to be exploited in transparent electronic and optoelectronic devices. The outputs of the project, the development of graphene-based transparent devices, will be fundamental to the commercial and the economic development of transparent electronics.
So far, chemical functionalization of graphene with different molecular species revealed that each molecular specie can be used to accumulate electrons or holes in graphene ( that is n- or p-type doping of graphene). This suggests the possibility that different doping of adjacent graphene areas can be used to engineer electron/hole interfaces also known as p-n junctions, which are the core of large part of nowadays electronic devices. Other chemical species such as hydrogen and fluorine atoms attached to graphene can modify its band structure by opening a band gap in the otherwise zero-gap semimetallic material, providing the opportunity to use graphene as a truly organic semiconductor. The potential afforded by the chemical functionalization of graphene materials is still in its infancy, and it holds great promise for future integrated optoelectronics.
The tremendous advantages of integrating devices on the same chip in electronics naturally suggest that the same be done with electronic and optoelectronic devices. However, integration of optoelectronic devices has proven to be a difficult challenge because of inherent incompatibilities. For example, a light-emitting diode based on a p-n structure has a structure quite different from the structure of any transistor. The exploitation of graphene will allow this incompatibility to be transcended. Intelligent schemes of functionalization of graphene hold the promise to accomplish the patterning of transparent standard resistors, capacitors and transistor structures integrated with light-emitting and detecting devices which constitutes a fundamental step towards applications such as smart windows. This pioneering research is at the core of this proposal.

Transparent devices are emerging technologies which will have a significant impact on society. Graphene is an ideal candidate for such technologies, as it is a sheet of carbon just one atom thick, with spectacular strength, flexibility, transparency, and electrical conductivity. This project is directed specifically at tuning the electronic properties of graphene so as to allow the full potential of this material to be exploited in transparent electronic and optoelectronic devices. The outputs of the project, the development of graphene-based transparent devices, will be fundamental to the commercial and the economic development of transparent electronics.
We have identified a number of industrial areas that would benefit from graphene-based transparent devices: photovoltaic devices, electronic circuits, sensors, detectors, displays and communication devices. The ability to embed transparent graphene-based electronic circuits, sensors and detectors into windows in public areas is of great interest and would improve national security. Transparent devices have the potential to improve social welfare by transforming the windscreens of cars, trains and airplanes into display controls and GPS-activated maps. Transparent communication devices embedded in windscreens or even wearable products would be of great relevance for commercial and military applications, and will also facilitate faster interactions and exchanges between individuals and communities. Transparent photovoltaic devices embedded in the windows in houses and offices will allow the production of electricity via solar energy. Graphene makes transistors more than 100 times faster than the silicon-based transistors used in today's electronics and therefore it could lead to electronic devices that are smaller, faster, and less power hungry than those made of silicon. Also, graphene could be orders of magnitude cheaper than the indium tin oxide (ITO) electrodes and the silicon transistors currently used in vast numbers in many industrial sectors. The use of graphene in these devices opens up an entirely new avenue towards the development of efficient and economical transparent optoelectronics, thus fostering the economic competitiveness of the United Kingdom. Apart from their expense, today`s transparent devices, based on ITO, can create major recycling problems. Many other materials that are currently used in these devices, such as carbon nanotubes or aromatic small molecules may be carcinogenic if they become airborne and are inhaled. The chances that graphene could be inhaled are very low since this material is a two-dimensional sheet which can be fabricated in large areas (100cmx100cm). Thus, by incorporating graphene in devices, the components of the future will not have negative effects on our health, will be much easier to recycle, and thereby will be environmentally more attractive.
Even though only 5 years have passed since graphene has been experimentally accessed, the recent demonstration of a transparent graphene-based touch screen clearly shows that the next few years can be regarded as realistic timescale for many of the benefits of the above described devices to be realised.
The interdisciplinary nature of the proposed project provides excellent educational and outreach opportunities for the staff and students working on the project. For example, the undergraduate and graduate students involved in the project will be exposed to the state-of-the-art tools of modern semiconductor research. The skills learned by the students in this project are highly marketable and will serve as a valuable asset for employment in industrial, governmental or academic institutions.
Our dissemination plan: hosting workshops, conferences, general public demonstrations and presentations, attending conferences and publication in peer-reviewed high-impact journals, will ensure that our work will enhance the knowledge of public as well as the public engagement with research.