Professor Donal Bradley
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P014_NELE_SEP13.qxp:Layout 1 8/9/11 09:59 Page 14 Professor Donal Bradley Prof Bradley graduated from Imperial College in 1983 with a first class BSc in Physics and received a PhD in 1987 from the University of Cambridge for his work on conjugated polymers. In 1989, he played a central role in the discovery of conjugated polymer electroluminescence, a move that led to his cofounding Cambridge Display Technology in 1992. He is director of the Imperial College London Centre for Plastic Electronics and cofounder and director of Molecular Vision. Prof Bradley also holds the Lee-Lucas Chair of Experimental Physics at Imperial College, is deputy principal of the Faculty of Natural Sciences and has just been named Pro Rector (Research), with responsibility for determining Imperial College’s strategic research investment priorities and for coordinating and developing the College’s external research relationships. Prof Bradley has published 500 papers to date and his papers have been cited more than 33,500 times. 14 13 September 2011 www.newelectronics.co.uk P014_NELE_SEP13.qxp:Layout 1 8/9/11 09:59 Page 15 Interview Professor Donal Bradley Seeing the light Graham Pitcher talks to a researcher who was ‘there at the start’ of the plastic electronics industry. ew people can reasonably claim to have been ‘there at the start’ of an materials and conjugated polymers. There are a lot of similarities,” he said, industry; Professor Donal Bradley was. His PhD at the University of “but Samsung’s success has shown there is real opportunity.” FCambridge’s Cavendish Laboratory focused on conjugated polymers; There has also been the awareness that plastic electronics technology work that would result in the establishment of Cambridge Display Technology could be used for things other than displays. “There has been a lot of work on (CDT) and a new industry – broadly categorised as ‘plastic electronics’. transistors, for example by Plastic Logic,” Prof Bradley pointed out. “And there So what was the attraction? “If you wanted to work in solid state at that has been an increase in interest in lighting applications, where the technology time,” he said, “it was all about low dimension semiconductors and the use of used to make displays can be applied to create larger area elements.” molecular beam epitaxy to create intricate structures. But people were also Prof Bradley admits that getting plastic electronics technology out of the beginning to think about using organic materials for semiconductors.” lab remains a challenge. “Part of the reason is that the UK has lost a lot of the Prof Bradley explained that he had always been larger companies that would have had an interest in interested in chemistry, as well as physics. “The “There is exceptionally these developments.” interface between the two seemed an interesting area in He said it is easier for Japanese companies, such as which to work, but I was coming at the problem from the strong university activity Sony, to pull technology through. “But there’s also the organic semiconductor side, rather than from the point scale of investment needed to commercialise the of view of III-V materials.” in the UK, but other technology,” he added. “Samsung is spending billions of Early work in organic materials research focused on parts of the world are dollars to improve device performance, while LG is the development and synthesis of conducting spending $3billion on an oled tv plant. The UK has seen materials that might act as metal replacements. “We catching up” start ups, but that is difficult to translate into major scale thought they would be better, weigh less and have activity and those companies tend to be bought.” better processability,” he recalled. “But we were also thinking about making Attempts to bring scale to the problem are being made through the optical switches with non linear properties.” establishment of plastic electronics Centres of Excellence; Prof Bradley is His PhD focused on how to process polymers in order to make ‘interesting director of one such centre located at Imperial College. “We also have hopes structures’. “I was looking to better understand physical properties,” he for Technology and Innovation Centres (TICs), but the level of investment explained, “understanding how charge was transported and some emission and support doesn’t look so encouraging in terms of them being able to properties.” But work by others had shown that organic materials could act as make a major impact.” leds and that sent Prof Bradley off in a new direction; into an area in which, he Nevertheless, Prof Bradley believes the UK remains a world leader in said, there ‘wasn’t a lot going on’. plastic electronics, at least for the moment. “There is exceptionally strong That new direction saw him working with CDT cofounders Richard Friend university activity in the UK, but other parts of the world are catching up. The and Jeremy Burroughes. “Richard had been looking to do organic transistors,” UK is still well placed and is one of the nations that people mention as a leader. Prof Bradley noted, “and organic leds came out of a discovery that involved But we can’t afford to be complacent because there are a lot of strong groups Richard, Jeremy and myself.” in other places who are forging ahead.” The resulting patent application described ‘an electroluminescent device Looking forward, Prof Bradley is turning his attention to photonics. “I’m comprising a semiconductor layer in the form of a thin dense polymer film ...’. researching organic materials as gain media for lasers. I’m also doing a lot of Prof Bradley was the corresponding author for the 1990 paper, published in work with metal oxide systems, using solution based approaches with a range Nature, that reported the discovery of conjugated polymer of fabrication methods. Zinc oxide and GaInZnO are very attractive options for electroluminescence. This paper – the most cited paper in molecular displays, where we’re looking to repace polysilicon.” electronic materials history – is believed to have launched plastic electronics. Prof Bradley believes UK science has had a good decade in terms of But plastic electronics has had a long gestation period. “The technology has funding in a period of change. “But we are being asked to justify more directly only been shown to be commercial in the last couple of years,” he said, “mostly the connection between investment in science and the impact of the work. I through the use of an active matrix oled in the Samsung Galaxy phone.” don’t think that’s a negative thing, but we have to be careful that we don’t Ironically, that technology derives from work originally performed by neglect the fundamental components of science in order to do more applied Kodak. “Our work has gone on in parallel, focusing on solution processed science. We need to preserve our strengths while looking for opportunities.” www.newelectronics.co.uk 13 September 2011 15.