̽��ֱ�� of Cambridge - Henning Sirringhaus

Twelve Cambridge researchers awarded European Research Council funding

sc604 — Thu, 22 Apr 2021 10:00:00 +0000

Two hundred and nine senior scientists from across Europe were awarded grants in today’s announcement, representing a total of €507 million in research funding. ̽��ֱ��UK has 51 grantees in this year’s funding round, the most of any ERC participating country.

ERC grants are awarded through open competition to projects headed by starting and established researchers, irrespective of their origins, who are working or moving to work in Europe. ̽��ֱ��sole criterion for selection is scientific excellence. ERC Advanced Grants are designed to support excellent scientists in any field with a recognised track record of research achievements in the last ten years. Apart from strengthening Europe’s knowledge base, the new research projects will also lead to the creation of some 1,900 new jobs for post-doctoral fellows, PhD students and other research staff.

Professor Melinda Duer from the Yusuf Hamied Department of Chemistry has been awarded a grant for her EXTREME project to explore the chemistry that happens when a biological tissue stretches or breaks.

So-called mechanochemistry leads to molecules being generated within the tissue that may be involved in communicating tissue damage to cells. Detecting and understanding this chemistry is highly relevant for understanding ageing, and for developing new therapeutics for degenerative diseases and cancer.

“This award means I can do the research I’ve been dreaming about for the last ten years,” said Duer. “I am extremely grateful to the European Research Council for giving me this amazing opportunity. ̽��ֱ��ERC is one of the few organisations that understands the need for longer-term funding for high-risk, high-reward research, which is essential for this project. I really couldn’t be more delighted and I can’t wait to get started!”

Professor Manish Chhowalla, from the Department of Materials Science and Metallurgy, received funding for his 2D-LOTTO project, for the development of energy-efficient electronics.

“This grant will enable our research group to realise the next generation of energy-efficient electronics based on two-dimensional semiconductors,” he said. “ ̽��ֱ��funding will also support a team of students, early career researchers and senior academics to address the challenges of demonstrating practical tunnel field effect transistors.”

Professor Henning Sirringhaus from the Cavendish Laboratory received funding for his NANO-DECTET project, for the development of next-generation energy materials. “Worldwide, only about a third of primary energy is converted into useful energy services: the other two thirds are wasted as heat in the various industrial, transportation, residential energy conversion and electricity generation processes,” said Sirringhaus. “Given the urgent need to mitigate the dangerous consequences of climate change, a waste of energy on this scale needs to be addressed immediately.

“Thermoelectric waste-heat-to-electricity conversion could offer a potential solution, but the performance of thermoelectric materials is currently insufficient. In this project we will use the unique physics of molecular organic semiconductors, as well as hybrid organic-inorganic semiconductors, to make efficient, low-temperature thermoelectric materials.”

Professor Marcos Martinon-Torres from the Department of Archaeology received funding for his REVERSEACTION project, which will study how societies in the past cooperated. “Many prehistoric societies did pretty well at maintaining rich and complex lives without the need for permanent power hierarchies and coercive authorities,” he said. “Arguably, they chose to cooperate, and not just to ensure survival. ̽��ֱ��lack of state structures did not stop them from developing and sustaining complex technologies, making extraordinary artefacts that required exotic materials, challenging skills and labour arrangements. I’m keen to understand why, but also how they managed.

“This grant couldn’t have come at a better time, as collective action is increasingly recognised as the only way to tackle some of our greatest global concerns, and there is value in studying how people collaborated in the past. With our labs freshly revamped through our recent AHRC infrastructure grant, we are ready to take on a new large-scale, challenging archaeological science project.”

Professor Marta Mirazon Lahr, also from the Department of Archaeology, was awarded funding for her NGIPALAJEM project, which will bring a new understanding of how the evolution of our species is part of a broader and longer African evolutionary landscape.

“My research is in human evolution, a field that advances through technical breakthroughs, new ideas, and critically, new fossils,” said Lahr. “A big part of my work is to find new hominin fossils in Africa, which requires not only supportive local communities and institutions, but long-term planning and implementation, a dedicated team, significant funds and the time to excavate, study, compare and interpret new discoveries. This new grant from the ERC gives me all this and more – and I just can’t wait to get started!”

Professor Richard Samworth’s RobustStats project will develop robust statistical methodology and theory for large-scale data. “Large-scale data are usually messy: they may be collected under different conditions, and data may be missing or corrupted, which makes it difficult to draw reliable conclusions,” said Samworth, from the Department of Pure Mathematics and Mathematical Statistics. “This grant will allow me to focus my time on developing robust statistical methodology and theory to address these challenges. Equally importantly, I will be able to build a group of PhD students and post-docs that will dramatically increase the scale and scope of what we are able to achieve.

Professor Zoran Hadzibabic from the Cavendish Laboratory was awarded funding for his UNIFLAT project. One of the great successes of the last-century physics was recognising that complex and seemingly disparate systems are fundamentally alike. This allowed the classification of the equilibrium states of matter into classes based on their basic properties. At the heart of this classification is the universal collective behaviour, insensitive to the microscopic details, displayed by systems close to phase transitions.

A grand challenge for modern physics is to achieve such a feat for the far richer world of the nonequilibrium collective phenomena. “Our ambition is to make a leading contribution to this worldwide effort, through a series of coordinated experiments on homogeneous atomic gases in two-dimensional (2D) geometry,” said Hadzibabic. “Specifically, we will study in parallel three problems – the dynamics of the topological Berezinskii-Kosterlitz-Thouless phase transition, turbulence in driven systems, and the universal spatiotemporal scaling behaviour in isolated quantum systems far from equilibrium. Each of these topics is fascinating and of fundamental importance in its own right, but beyond that we will experimentally establish an emerging picture that connects them.”

Dr Helen Williams from the Department of Earth Sciences said: “By funding the EarthMelt project, the ERC has given me the amazing opportunity to study the early evolution of the Earth and its transition from a largely molten state to the habitable planet we know today. This funding will also help me to develop exciting new instrumentation and analytical techniques, and, most importantly, mentor and support the next generation of PhD students and postdoctoral researchers working in geochemistry.”

Professor Sir Richard Friend from the Cavendish Laboratory has been awarded funding for his Spin Control in Radical Semiconductors (SCORS) project, which will explore the electronic properties of organic semiconductors that have an unpaired electron to give net magnetic spin. ̽��ֱ��project is based on a recent discovery that this unpaired electron can couple strongly to light, allowing very efficient luminescence in LEDs. Friend’s group will explore new combinations of optical excited states with magnetic spin states. This will allow new designs for LEDs and solar cells, and opportunities to control the ground state spin polarisation in spintronic devices.

Professor Christopher Hunter’s InfoMols project is focused on synthetic information molecules. “ ̽��ֱ��aim of our project is replication and evolution with artificial polymers,” said Hunter, from the Yusuf Hamied Department of Chemistry. “ ̽��ֱ��timeframe for achieving such a breakthrough is unpredictable, and it is the flexibility provided by an ERC award that makes tackling such challenging targets possible.”

Professor Mark Gross from the Department of Pure Mathematics and Mathematical Statistics received funding for his Mirror symmetry in Algebraic Geometry (MSAG) project, and Professor Geoffrey Khan from the Faculty of Asian and Middle Eastern Studies was awarded funding for ALHOME: Echoes of Vanishing Voices in the Mountains: A Linguistic History of Minorities in the Near East.

Twelve ̽��ֱ�� of Cambridge researchers have won advanced grants from the European Research Council (ERC), Europe’s premier research funding body. Their work is set to provide new insights into many subjects, such as how to deal with vast scales of data in a statistically robust way, the development of energy-efficient materials for a zero-carbon world, and the development of new treatments for degenerative disease and cancer. Cambridge has the most grant winners of any UK institution, and the second-most winners overall.

̽��ֱ�� of Cambridge

Top, left to right: Helen Williams, Richard Friend, Richard Samworth, Melinda Duer. Bottom, left to right: Chris Hunter, Marta Mirazon Lahr, Marcos Martinon-Torres, Manish Chhowalla

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

A new spin on organic semiconductors

sc604 — Tue, 26 Mar 2019 00:00:59 +0000

̽��ֱ��international team from the UK, Germany and the Czech Republic has found that these materials could be used for ‘spintronic’ applications, which could make cheap organic semiconductors competitive with silicon for future computing applications. ̽��ֱ��results are reported in the journal Nature Electronics.

‘Spin’ is the term for the intrinsic angular momentum of electrons, which is referred to as up or down. Using the up/down states of electrons instead of the 0 and 1 in conventional computer logic could transform the way in which computers process information.

Instead of moving packets of charge around, a device built on spintronics would transmit information using the relative spin of a series of electrons, known as a pure spin current. By eliminating the movement of charge, any such device would need less power and be less prone to overheating – removing some of the most significant obstacles to further improving computer efficiency. Spintronics could therefore give us faster, energy-efficient computers, capable of performing more complex operations than at present.

Since organic semiconductors, widely used in applications such as OLEDs, are cheaper and easier to produce than silicon, it had been thought that spintronic devices based on organic semiconductors could power a future computer revolution. But so far, it hasn’t worked out that way.

“To actually transfer information through spin, the electron’s spin needs to travel reasonable distances and live for a long enough time before the information encoded on it is randomised,” said Dr Shu-Jen Wang, a recent PhD graduate of the ̽��ֱ�� of Cambridge’s Cavendish Laboratory, and the paper’s co-first author.

“Organic semiconductors have not been realistic candidates for spintronics so far because it was impossible to move spins around a polymer circuit far enough without losing the original information,” said co-first author Dr Deepak Venkateshvaran, also from the Cavendish Laboratory. “As a result, the field of organic spintronics has been pretty quiet for the past decade.”

̽��ֱ��internal structure of organic semiconductors tends to be highly disordered, like a plate of spaghetti. As such, packets of charge don’t move nearly as fast as they do in semiconductors like silicon or gallium arsenide, both of which have a highly ordered crystalline structure. Most experiments on studying spin in organic semiconductors have found that electron spins and their charges move together, and since the charges move more slowly, the spin information doesn’t go far: typically only a few tens of nanometres.

Now, the Cambridge-led team say they have found the conditions that could enable electron spins to travel far enough for a working organic spintronic device.

̽��ֱ��researchers artificially increased the number of electrons in the materials and were able to inject a pure spin current into them using a technique called spin pumping. Highly conductive organic semiconductors, the researchers found, are governed by a new mechanism for spin transport that transforms them into excellent conductors of spin.

This mechanism essentially decouples the spin information from the charge, so that the spins are transported quickly over distances of up to a micrometre: far enough for a lab-based spintronic device.

“Organic semiconductors that have both long spin transport lengths and long spin lifetimes are promising candidates for applications in future spin-based, low energy computing, control and communications devices, a field that has been largely dominated by inorganic semiconductors to date,” said Venkateshvaran, who is also a Fellow of Selwyn College.

As a next step, the researchers intend to investigate the role that chemical composition plays in an organic semiconductor’s ability to efficiently transport spin information within prototype devices.

̽��ֱ��research was coordinated by Professor Henning Sirringhaus at the Cavendish Laboratory and funded through a European Research Council (ERC) Synergy Grant jointly held by the ̽��ֱ�� of Cambridge, Imperial College London, ̽��ֱ�� of Mainz, Czech Academy of Sciences and Hitachi Cambridge Laboratory.

Reference:
Shu-Jen Wang, Deepak Venkateshvaran et al. ‘Long spin diffusion lengths in doped conjugated polymers due to enhanced exchange coupling.’ Nature Electronics (2019). DOI: 10.1038/s41928-019-0222-5

Researchers have found that certain organic semiconducting materials can transport spin faster than they conduct charge, a phenomenon which could eventually power faster, more energy-efficient computers.

Organic semiconductors have not been realistic candidates for spintronics so far because it was impossible to move spins far enough without losing the original information

Deepak Venkateshvaran

Deepak Venkateshvaran and Nanda Venugopal

Hand sketch of an organic lateral spin pumping device

Yes

Bright future for British solar company

bjb42 — Thu, 16 Sep 2010 00:00:00 +0000

Cambridge Enterprise, the ̽��ֱ�� of Cambridge’s commercialisation office, and the Carbon Trust have announced the launch of Eight19 Limited, a new solar energy company which will develop and manufacture high performance, lower cost plastic solar cells for high-growth volume markets.

Spun-out from the Carbon Trust's Cambridge ̽��ֱ��-TTP Advanced Photovoltaic Research Accelerator, this latest commercial phase will focus efforts on developing product prototypes, backed by a £4.5m investment from the Carbon Trust and leading international specialty chemicals company Rhodia.

Eight19, so called as it takes 8 minutes and 19 seconds for light to travel from the sun to the earth, has been created in partnership with Professor Sir Richard Friend, Professor Henning Sirringhaus and Professor Neil Greenham of Cambridge's internationally renowned Cavendish Laboratory, and technology development company TTP.

With improvements in efficiency and lifetime, breakthroughs in organic photovoltaic technology could provide solar power at a price substantially lower than that offered by 1st and 2nd generation technologies for certain applications, which could open up new markets for solar.

Eight19's focus on the low cost potential of solar cells made with semiconducting plastics (also known as organic photovoltaics, or OPV) is built on the Cavendish Laboratory's capability to develop techniques for fabricating large scale plastic electronic devices on flexible materials using roll-to-roll processes. ̽��ֱ��company will continue to be actively engaged with the Cavendish and its innovative research output.

̽��ֱ��market for organic solar cells has the potential to reach $500 million by 2015 and to grow four fold to $2 billion by 2020 (Nanomarkets, 2009) driven by applications such as building-integrated photovoltaics, and could save up to 900 million tonnes of CO2 by 2050 - some 1.5 times the UK's current annual emissions.

̽��ֱ��Eight19 team is pursuing a design-for-manufacture strategy that focuses on the unique attributes of organic photovoltaics, combining both specific product performance characteristics and low cost of energy.

Unlike other more familiar thin film solar platforms, organic solar cells are not inherently limited by constraints around material supply and toxicity, and benefit from a number of fundamental advantages including potentially very low cost production enabled by low temperature and high throughput processing typical of plastic films. Organic solar cells potentially deliver further value throughout the supply chain, from ease of installation for construction companies to producers seeking simplified manufacturing integration.

Dr Robert Trezona, Head of R&D at the Carbon Trust said, " ̽��ֱ��launch of Eight19 and the deployment of low cost organic solar cells could help to revolutionise solar power production by opening up new markets. Cost reduction through the development of advanced technology and innovative design are key to driving forward mass production and making solar power more affordable."

"This investment is perfectly in line with our strategy to explore new promising market segments fitting with our sustainable development commitment. Furthermore, we are convinced that open innovation is key to leverage our research and development capability. We are happy to work in close partnership with prominent scientists to develop this breakthrough technology", explains Pascal Juery, Group Executive Vice-President of Rhodia.

Professor Sir Richard Friend, Co-founder of Eight19 commented, "This represents a great opportunity to transfer new technology out of the university, based on recent advances in fundamental science. Solar cells made with organic semiconductors work very differently to those made with silicon and are closer in operating principle to photosynthesis in green plants."

A world class management team underpins the technology development, with significant track record in making low cost applications using scalable roll-to-roll technology. Co-founder and Board Director Professor Sir Richard Friend is a world expert who pioneered the study of the electronic properties of a class of plastics called conjugated polymers and revolutionised the understanding of using these materials to make plastic semiconductors. He also previously co-founded Cambridge Display Technology (CDT) and Plastic Logic.

Solar energy company to develop and manufacture high performance, lower cost plastic solar cells.

Solar cells made with organic semiconductors work very differently to those made with silicon and are closer in operating principle to photosynthesis in green plants.

Professor Sir Richard Friend, Co-founder of Eight19

Clearly Ambiguous from Flickr

Solar Mosaic

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Yes

Plastic Logic: from innovation to impact

bjb42 — Sat, 01 Aug 2009 00:00:00 +0000

̽��ֱ��path from innovation to impact can be long and complex. Here we describe the fascinating story behind the development of a new type of electronic reader.

̽��ֱ��story of Plastic Logic started in the mid-1980s when Professor Sir Richard Friend – then a lecturer in the Department of Physics at the ̽��ֱ�� of Cambridge – began to work on organic semiconductors [see Glossary below]. ‘My interest was pure curiosity,’ says Friend, who is now the Cavendish Professor of Physics at the ̽��ֱ�� of Cambridge. He was interested, he explains, in gaining a basic understanding of how electrons might be made to move in carbon-based semiconductors, rather than being driven by the prospect that his research might be commercially useful.

Semiconductors – materials that conduct electricity under some conditions but not others – are used to make the integrated circuits that run computers and other electronic devices. Silicon is the best known semiconductor but, in the 1960s, researchers discovered that some organic molecules also behave as semiconductors. Specifically, small molecules that contain carbon atoms linked by alternating single and double bonds – so-called conjugated molecules – behave as semiconductors because some of their electrons are delocalised and ‘shared’ throughout the molecule. Friend wanted to know whether polymers made from building blocks of conjugated molecules would also behave as semiconductors. ‘We were interested in this type of molecule because we thought that, if they did behave as semiconductors, we might be able to use them to make electronic devices simply by dissolving the polymers in a solvent and then painting them onto a surface,’ says Friend.

By 1988, Friend’s research group had managed to make a transistor from the conjugated polymer polyacetylene. But, notes Professor Henning Sirringhaus, Hitachi Professor at the ̽��ֱ�� of Cambridge and Friend’s colleague since 1997, ‘the performance of this polymer or plastic transistor was very poor because the speed at which electrons and holes move through polyacetylene – a property called mobility – is much lower than in silicon. Plastic transistors were pretty much a scientific curiosity at that point, although they did provide a useful device for studying the electrical properties of new materials.’

A serendipitous discovery

Friend’s team now started to investigate whether better transistors could be made from other conjugated polymers. ‘We thought that a poorly studied compound called poly(p-phenylene vinylene), PPV, looked promising,’ says Friend, ‘and we began a collaboration with Andrew Holmes, a natural products scientist then working in the Department of Chemistry in Cambridge, to make PPV and to use it to make transistors.’

Unfortunately, PPV was not ideal for transistors – it was too good an insulator. But rather than giving up on PPV, the researchers decided to measure its insulating properties. ‘Instead of making a parallel electrode arrangement as we do for transistors, in February 1989 we made a stacked electrode arrangement as we do in diodes and sandwiched the PPV between the two electrodes to measure its insulating abilities,’ explains Friend.

By good fortune, Dr Jeremy Burroughes, who had made the first polyacetylene transistors while a PhD student in Friend’s laboratory, used a thin, semi-transparent layer of aluminium to make the top electrode in this PPV-containing device. When Burroughes (who is now the Chief Technology Officer at Cambridge Display Technology, CDT) applied a voltage to the device, he unexpectedly saw green light coming through the electrode. Friend immediately contacted Dr Richard Jennings (Director of Technology Transfer and Consultancy Services, Cambridge Enterprise Ltd) in what was then the ̽��ֱ��’s industrial liaison office to tell him about the strange, light-emitting piece of plastic and to ask for advice on patenting this discovery.

‘As soon as Richard explained what he had seen, we began to think about applications,’ says Jennings. ‘Plastic light-emitting displays, light-emitting clothing, plastic TV screens – it didn’t take much imagination to see how these polymer light-emitting diodes [P-LEDs] might be used and my advice was to patent the invention immediately.’ A particular appeal of light-emitting plastics, say both Friend and Jennings, was that these materials could be solution-processed or painted over a large area, a much simpler process than that needed to make liquid crystal displays (LCDs), the up-and-coming display technology in the late 1980s.

Patents for P-LEDs were filed in April 1989 and April 1990. Then, in October 1990, the researchers published a letter in the journalNatureentitled ‘Light-emitting diodes based on conjugated polymers’. ‘ ̽��ֱ��rest of the world simply dived in after we published. We had scores of imitators and our patent was challenged on several occasions,’ says Friend.

But, despite the academic interest in P-LEDs, Friend failed to find a UK electronics company to license and develop the invention. ‘It wasn’t that the companies weren’t willing to license the patent,’ stresses Friend. ‘It was more that they did not see organic light-emitting diodes as a core business and I was concerned that they would simply sit on our idea and not do the work needed to develop it. ̽��ֱ��quickest single way to kill a good idea is to put it into the wrong hands,’ comments Friend.

So, in 1992, Friend, with help from the ̽��ֱ�� of Cambridge and local seed venture capital, founded CDT. Although the original intention was that CDT would be a materials manufacturing company, CDT has concentrated on developing new technologies and licensing them to other companies. For example, in association with various industrial partners, CDT has developed a method to make P-LED displays using inkjet printing, thin-film transistors to stimulate the P-LED-containing pixels in displays, and polymers that emit red or blue light when stimulated instead of green light. In 2004, CDT was floated on the NASDAQ National Market and, in 2007, it was acquired by the Sumitomo Chemical Company, which maintains substantial R&D activity in and around Cambridge.

Importantly, says Friend, a strong symbiotic relationship has developed between CDT and the scientists working in the ̽��ֱ��: ‘Over the years, we have sent a lot of ideas to CDT but in return we have had access to the materials and methods that CDT has developed and this has helped us to push our fundamental research along much faster than would have been possible if we had had to do everything in the ̽��ֱ��.’

Back to transistors

While P-LEDs were being developed, some work continued in Cambridge and elsewhere on plastic transistors. Because silicon-based transistors were so good, explains Sirringhaus, ‘there wasn’t any commercial drive to work on plastic transistors and probably fewer than ten groups worldwide were working on the problem.’ Adds Friend, ‘it was really a matter of waiting for new materials to be made, waiting for the technology and science to develop to a stage where we could take the transistors forward.’

Then, in 1997, a way was found to increase the mobility of polymer semiconductors. ̽��ֱ��problem with the original polymer semiconductors had been that the long-chain molecules within these substances were disordered – ‘like a bowl of spaghetti’, says Sirringhaus. As the charge moved through this disordered mass, it encountered configurations where it didn’t know where to go and this reduced the material’s mobility. ̽��ֱ��polymer chains were disordered because, to process polymer solutions,

flexible side chains have to be attached to the polymer chains. Unfortunately, these side chains made the polymer disordered and electrically poorly conducting. ̽��ֱ��1997 breakthrough was the discovery of a way to deposit materials from polymer solutions that consist of alternating layers of conjugated polymers lying in a plane and insulating side chains. ‘ ̽��ֱ��mobility in the conjugated plane can be very high and it doesn’t matter about the mobility elsewhere in the structure,’ explains Sirringhaus.

Although the demonstration that the mobility of polymer semiconductors could rival that of inorganic semiconductors like silicon was important, before the researchers could persuade large companies or venture capitalists to invest time and/or money in their discovery, they still had to show that their new material could be used to make transistors in a practical manner.

‘At that time, we were developing methods to use inkjet printing to deposit P-LEDs onto substrates so we started to investigate whether the same process could be used to print transistors,’ says Sirringhaus. Within a few months, Sirringhaus and PhD student Takeo Kawase, on secondment from Seiko Epson, had printed a few transistors onto small substrate chips and had shown that these simple circuits performed reasonably well. ‘We now had a credible story on the materials and a credible way to make devices from them so we began to think about commercialisation,’ says Sirringhaus. Indeed, says Friend, ‘I had a strong sense that the future seminal events in the development of organic transistors were going to be engineering events, not science events, and I believed that these were most likely to happen in a well-focused industrial environment.’

Plastic Logic is founded

With this in mind, the researchers approached the entrepreneur and venture capitalist Dr Hermann Hauser, a co-founder of Amadeus Capital Partners (Cambridge) and an early investor in CDT, to see whether he would invest money in the commercial development of organic polymer transistors.

‘I remember visiting Richard and his group in the Cavendish,’ says Hauser. ‘They only had a few transistors working at this time [1998] and when they stopped working they prodded them with toothpicks!’ Luckily, Hauser, with his background in physics and interest in electronics, instantly recognised that Friend, Sirringhaus and their colleagues had made a very fundamental breakthrough and, with his help, Plastic Logic was formed in January 2000.

What is so special about plastic transistors?

When Plastic Logic started, all the electronic displays in the world were made on glass. Displays like those attached to computers contain millions of pixels, each of which is switched on and off by an individual silicon transistor. To produce these transistors, amorphous (non-crystalline) silicon is processed at high temperatures. Consequently, silicon-based transistors can only be produced on a substrate like glass that can withstand high temperatures; a plastic substrate would melt or deform. But displays that contain glass are heavy, rigid and fragile and unsuitable for use in anything but very small mobile displays. ̽��ֱ��production of plastic transistors, by contrast, does not require high temperatures so they can be laid down on plastic substrates that are much lighter, and more flexible and robust than glass. This means that large portable displays can be made by using plastic instead of silicon transistors.

Plastic transistors have a second advantage over silicon transistors when it comes to making large displays. Electronic circuits contain many layers that have to be accurately aligned with each other. In a large display, the dimensions of the substrate inevitably change slightly during the production process. Silicon-based displays are made using a lithographic process in which patterns are sequentially deposited onto substrates using metal masks. Unfortunately, any small changes in the dimensions of the substrate during the production process mean that the masks do not line up accurately and the resultant display is defective. With displays that contain plastic transistors, computers drive the inkjet printers that make the various layers of the device so it is possible to allow for changes in the substrate’s dimensions.

From single transistors to an electronic reader

‘When Plastic Logic was founded,’ says Jennings, ‘there wasn’t a clear business plan but Hermann Hauser was a very far-sighted investor who, knowing the track record of Richard Friend and Henning Sirringhaus, was willing to put money into their company to see where it would go.’ Over the next few years, Plastic Logic raised considerable sums of money to support its work and by 2006 it had developed its plastic transistor technology sufficiently to produce a display containing a million transistors. It had also developed an application for these displays – a plastic electronic reader. Since 2006, Plastic Logic has raised more than US$100 million to build a large manufacturing plant in Dresden (Germany); its research and development department still remains in Cambridge but its corporate headquarters is now based in Mountain View (California, USA). Trials of the electronic reader with key customers should be completed by the end of 2009 and commercial production will be rolled out in 2010.

̽��ֱ��electronic reader, which has an A4 screen that is about as heavy and thick as a sheet of paper, uses an ‘active matrix display’, an array of pixels in which each pixel contains minute plastic capsules filled with a liquid that contains black and white particles. These particles have different charges so that when an electric current is applied to a pixel, either the white or the black particles move to the front of the capsule and the pixel appears white or black. A plastic transistor behind each pixel applies the electric charges and the whole device is printed onto a thin, flexible sheet of plastic.

Plastic Logic’s electronic reader will enable users to read their own documents anywhere and will give them access to newspapers and books and, according to Friend, Sirringhaus and Hauser, it has several advantages over existing electronic readers such as Amazon’s Kindle. Its display is lighter and more robust than the glass-based displays in other readers and, because the display is bigger than those in other readers, it is more suitable for accessing newspapers. Also, the device uses very little energy because, unlike other readers, the display in the Plastic Logic reader does not need a back light. Consequently, once a page is set, it can remain in place without consuming any energy. Thus, users should be able to take a Plastic Logic reader away on holiday, for example, without having to take a battery charger.

Other hopes for plastic electronics – the need for continuing basic research

Plastic Logic should produce several hundred thousand electronic readers in 2010 and, in later years, it could be producing millions of units. But Hauser believes that plastic electronics will have much broader applications in the future. While Plastic Logic was developing its electronic reader, he explains, basic research was continuing in the ̽��ֱ�� of Cambridge, where Sirringhaus’ group recently made an important breakthrough by discovering how to make a CMOS plastic transistor.

‘CMOS’ stands for complementary metal oxide semiconductor, a type of semiconductor that can be used to produce a combined n-type and p-type transistor. This type of transistor is needed to build complex devices like computer processors but for many years it seemed that it would be impossible to build plastic transistors with the properties of CMOS transistors – polymer semiconductors were all p-type semiconductors because they all carried current in the form of holes. Then, in 2005, Sirringhaus and his colleagues showed that the reason why th

ere were no n-type polymer semiconductors was because the electrons were being trapped at the interface between the semiconductor and adjacent insulators. By studying this interface, the researchers were able to produce an n-type polymer semiconductor, which opened up the possibility of designing the CMOS circuits that are necessary for the development of a broad plastic electronics industry.

However, Friend, Sirringhaus and Hauser stress that relatively little is known about polymer semiconductors and, because these materials are so different from silicon, it is not possible to rely on established semiconductor physics to understand how they work. Thus, it is essential that fundamental research on polymer semiconductors continues to be funded within UK universities. This, together with improved governmental support for the companies involved in plastic electronics, should ensure that the UK’s current lead in the field of plastic electronics is retained and that the UK reaps the financial rewards of the groundbreaking, curiosity-driven basic research in which Friend, Sirringhaus and their colleagues excel.

Glossary

Conductor:a material that can carry an electric current.

Diode:an electronic component with two electrodes that conducts electric current in only one direction.

Insulator:a non-conductor of electric current.

Light-emitting diode (LED):a diode that emits light when current passes through it. LEDs are used in many electronic devices.

Liquid crystal display (LCD):a display technology in which a current passing through a liquid crystal solution makes the crystals line up so that light cannot pass through them.

Organic semiconductor:a carbon-based semiconductor.

Pixels:picture elements, the units from which images are made on televisions and computer monitors.

Plastic (or polymer) semiconductor:a semiconductor made from an organic polymer.

Plastic (or polymer) transistor:a transistor that contains a plastic semiconductor.

Semiconductor:a substance that conducts electricity only under some conditions. ̽��ֱ��conductivity of semiconductors can be increased by applying heat, light or a voltage. Ann-typesemiconductor carries current mainly in the form of negatively charged electrons. Ap-typesemiconductor carries current mainly as electron deficiencies calledholes; a hole has an equal and opposite electric charge to an electron.

Transistor:a semiconductor device used to amplify or switch electronic signals. A small current across one pair of terminals in a transistor controls the current at another pair of terminals, either amplifying the original current or turning the current on and off in a circuit.

̽��ֱ��path from innovation to impact can be long and complex. Here we describe the fascinating story behind the development of a new type of electronic reader.

‘Plastic light-emitting displays, light-emitting clothing, plastic TV screens – it didn’t take much imagination to see how these polymer light-emitting diodes might be used and my advice was to patent the invention immediately.’

Dr Richard Jennings

Plastic Logic

Electronic reader

A tale of two innovations

We are often taken aback by the sudden appearance of a new innovation that has clear economic or clinical impact. Just how did these innovations arise?

Academic scientists working in universities are driven to do their research for many reasons. Some see their research as a way to develop new drugs or to build more powerful computers, for example. Many academic scientists, however, are simply curious about the world around them. They may want to understand the intricacies of the immune system or how the physical structure of a material determines its properties at a purely intellectual level. They may never intend to make any practical use of the knowledge that they glean from their studies.

Importantly, however, even the most basic, most fundamental research can be the starting point for the development of materials and technologies that make a real difference to the everyday life of ordinary people and that bring economic benefit to the country. Indeed, said Dr Richard Jennings, Director of Technology Transfer and Consultancy Services at Cambridge Enterprise Ltd, ̽��ֱ�� of Cambridge, ‘what universities are good at is fundamental research and it is high-quality basic research that generates the really exciting ideas that are going to change the world.’

But it takes a great deal of time, money and commitment to progress from a piece of basic research to a commercial product, and the complex journey from the laboratory to the marketplace can succeed only if there is long-term governmental support for the academic scientists and their ideas as well as the involvement of committed commercial partners and well-funded technology transfer offices.

Two particular stories illustrate the long and complex path taken from the laboratory to commercial success by two very different ̽��ֱ�� of Cambridge innovations. In the case of Plastic Logic, basic research on materials called organic semiconductors that started in the 1980s and that continues today has led to the development of a new type of electronic reader that should be marketed in early 2010 and, more generally, to the development of ‘plastic electronics’, a radical innovation that could eventually parallel silicon-based electronics. For Campath, the journey started just before Christmas in 1979 in a laboratory where researchers were trying to understand an immunological concept called tolerance. Now, nearly three decades later and after a considerable amount of both basic research and commercial development, Campath-1H is in Phase 3 clinical trials for the treatment of relapsing–remitting multiple sclerosis.

‘Both innovations are likely to have profound impacts over the next two years and it is important to recognise the deep temporal roots of both,’ said Professor Ian Leslie, Pro-Vice-Chancellor for Research.

Professor Leslie highlighted that an important lesson to draw from these stories ‘is the need for universities and other recipients of public research funding to implement and develop processes to support the translation of discovery to impact or, more generally, to develop environments in which the results of discovery can be taken forward and in which external opportunities for innovation are understood.’

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Sunny times ahead for solar power

ns480 — Fri, 08 Feb 2008 11:57:11 +0000

Photovoltaic (PV) solar panels offer great promise as a source of clean and renewable electricity generation but the high cost of manufacturing the silicon-based PV panels has been a prohibitive drawback to their use. A new research and development programme led by Professor Sir Richard Friend, Dr Neil Greenham and Professor Henning Sirringhaus at the ̽��ֱ�� of Cambridge’s Cavendish Laboratory, in collaboration with ̽��ֱ��Technology Partnership, hopes to solve this problem. ̽��ֱ��team are using a plastic-based technology to create the solar cells. A prototype has already been built and the new funding will allow scaling up to large sheets of PV film that can be sited on windows or roofs to capture solar energy.

By 2017, the aim is for these plastic solar cells to be delivering 1GW of power, equivalent to carbon dioxide savings of more than 1 million tonnes per year. ‘This is a timely opportunity to build on technology developed in the ̽��ֱ��,’ said Professor Friend. ‘We will capitalise on the local Cambridge strengths in taking science to manufacturing.’

̽��ֱ��Carbon Trust is funding the initiative. Tom Delay, Chief Executive, explained the importance of the research: ’We believe this exciting new organic PV technology is our best shot at dramatically reducing the cost of solar PV to the point that, in the next 10 years, it could become as cheap as the power currently delivered to our homes.’

For more information, please contact Dr Neil Greenham(ncg11@cam.ac.uk) or the Carbon Trust (www.carbontrust.co.uk; Tel: +44 (0)20 7544 3100).

A new initiative funded by the Carbon Trust hopes to make solar power an affordable choice for homeowners within 10 years.

We will capitalise on the local Cambridge strengths in taking science to manufacturing.

Professor Friend

Cambridge Display Technology

Prototype solar panel

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