Double success for Imperial researchers developing the solar cells and plastic electronics of the future

Highly-cited honour for two Imperial-authored papers<em> - News</em>

By Danielle Reeves
Monday 23 February 2009

Two research papers authored by Imperial's plastic electronics research team have emerged as the two most highly cited papers published in Nature Materials in 2006.

The first paper, reporting research led by Professors Donal Bradley and Jenny Nelson from the Department of Physics, and Professor James Durrant from the Department of Chemistry, outlines ways of improving the performance of solar power cells made from organic materials, such as plastics. Since publication the paper has been cited in 253 subsequent scientific studies, according to Thomson Sciencewatch's Essential Science Indicators, making it the most highly cited paper published in Nature Materials in 2006.

Solar cells made from plastics could provide a low-cost alternative to traditional solar cells made from silicon and other inorganic materials, provided their efficiency can be improved to make them competitive with the traditional products on the market.

The development of plastic semiconductors could dramatically drive down the cost of flat panel screens

The study showed that making small changes to the chemical structure of one of the two materials used to make plastic solar cells improves the way the two materials mix together. This creates a more efficient solar cell.

Professor Jenny Nelson said: "We showed that by changing the chemical structure of the plastic component we could control the way in which molecules assemble together in the plastic film. Optimising this process leads to better performance from the solar cell."

Professor Nelson adds that the success of their paper is probably due, in part, to the efficiency improvements that they produced in organic solar cells, as a result of their structural manipulations: "In 2006 when we carried out this research we successfully created a solar cell which was 4.4% efficient – the best organic solar cell efficiency in the world at that time."

Following closely behind with 201 citations, the second most highly cited paper from this journal in 2006 was led by Imperial chemist Professor Iain McCulloch, in collaboration with Dr Martin Heeney from Queen Mary University of London, who is set to join Imperial's Chemistry department this year.

Their paper described a new plastic semiconductor that allows an electrical charge to pass through it at speeds never before seen, a discovery which could dramatically drive down the cost of flat panel screens.

The new plastic could one day replace silicon as the semiconductor used in the electronic components that control the displays in computer and television monitors and in so-called radio frequency identification chips, which are used to keep track of store inventories, fleets of trucks and herds of cattle.

Professor McCulloch said: "The paper illustrates a key relationship between the assembly of polymer molecules into organised structures, and the resultant improvements that arise in electrical performance. These results offer the possibility of printable electronics using semiconducting polymer inks."

Professor Donal Bradley FRS, Lee-Lucas Professor of Experimental Physics and Director of the new Plastics Electronics Centre, which has been recently established at the College, commented on the success of the papers, saying:

"Plastic electronics is predicted to become a multibillion dollar global industry and has the potential to contribute strongly to a more sustainable future via energy efficient displays and lighting and low cost solar energy conversion. It is also attracting attention as a technology platform that can enable the widespread deployment of electronic sensors and control circuits, including those used in point of care medical diagnostics.

"Longer term, plastic electronics offers the prospect of novel photonic devices for local area data communication networks, such as are increasingly needed within the automotive and aeronautics sectors. The impact of these two papers reflects the strength of the programme we have established at Imperial College and bodes well for future success in supporting the development of this fledgling technology via extensive and detailed fundamental studies."

In addition to the new Plastic Electronics Centre, research in this area at Imperial has been further bolstered by a recent £6 million award from the Engineering and Physical Sciences Research Council (EPSRC) for a Doctoral Training Centre in plastic electronics. This training centre, which will open its doors in October this year, will initially support 50 postgraduate students over five years to research plastic electronic materials over five years, and aims to develop the next generation of world-class researchers in this field.

Professor Maggie Dallman, Principal of Imperial's Faculty of Natural Sciences, congratulated the researchers, saying: "Plastic electronics is a very exciting area of technologically important research, in which Imperial is a world leader. The influence these two papers are having on the scientific community is testament to the high quality, groundbreaking work we’re contributing to this field."

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