Nanotechnology will lead to more efficient and reliable solar cells

(Nanowerk News) New ECS Professor Darren Bagnall manages an energetic research group within the Nano Group that is investigating new types of solar cell based on nanotechnology.
He is one of a number of staff in the School of Electronics and Computer Science (ECS) who will be moving this month into the new Mountbatten Building, a 55M development for leading-edge research in nanotechnology and optoelectronics.
This is an incredibly exciting time for us', he says. 'Over the last few years there has been a massive increase in funding for research into renewable energy. Even with currently available technology photovoltaics will probably provide 50 per cent of the world's energy in around 40 years time, but what we actually want is to use nanotechnology so that solar cells are efficient and reliable, and yet so cheap that they can be afforded by the tens of thousands of villages around the world that currently do not have electricity.'
Darren Bagnall
Darren Bagnall
Some of Darren's most eye-catching work includes the use of nanostructures that copy the complex patterns that produce extreme colour effects on moth-eyes and butterfly wings. He is also exploring the use of metallic nanoparticles plasmonics - that can help to trap light within thin semiconductor layers in a solar cell.
Growing up in Stoke-on-Trent, Darren was a keen science student from an early age. His interest in electronics was probably triggered when his Dad, who was in the nightclub business, brought home a broken pinball machine. 'It was no use to anyone', says Darren, 'but provided a whole load of sensors, switches and actuators that my brother and I used to build some crazy systems.' The interest that developed from this led Darren to do a degree in electronics at Salford University, where he became interested in semiconductor devices and went on to do a PhD in Photovoltaics.
After his PhD, Darren went to Strathclyde University to develop blue laser diodes. Although they could not be manufactured in the 80s, blue laser diodes were known to be important requirements particularly for what has become known as Blu Ray technology. At Strathclyde Darren developed mono-layer quantum well lasers based on ZnCdSe, and was subsequently offered a research fellowship in Japan at the prestigious Institute of Materials Research of Tohoku University. During this time he made one of his most notable research contributions in producing the first zinc oxide laser. 'This paper has helped kick-start a whole new research front and our paper now has over 1000 citations,' he says.
After spending three years in Japan, Darren wanted to return to the UK and he was delighted when he was appointed to a lectureship at ECS. 'I found the infrastructure and the cleanrooms amazing', he said. 'I was also really struck by the tremendous ambition and energy in ECS.'
Since arriving in Southampton Darren has had the opportunity to use his experience in optoelectronics and apply it to working with silicon, a material that can be made to interact with light only with extreme ingenuity: 'What we can do is create nanoscale features that are much smaller than the wavelength of light and thereby trick light into doing things it wouldn't normally do.'
For example, Darren has shown that if tens of thousands of nanoscale swastikas are arranged on a square millimetre, he can 'twist' light in accordance with the rotation of the swastikas and thereby create artificial 'metamaterials' that control polarization. It is this concept of the metamaterials and their application to photovoltaics that drives his current research.
Darren's commitment and optimism carried him through the fire which destroyed 50M worth of ECS research three years ago. Although each of his team lost at least a year's work, he feels the episode has now given them a unique opportunity.
'We are now in a position where we have a great deal of knowledge and yet have the chance to redesign our experiments right from the very beginning,' he said. 'Although this will take us some time, I expect it to yield some very exciting results.'
Darren's first aim in the new facility will be to make the first 20 per cent efficient solar cell based on thin film silicon 'It won't be easy', he says, 'but we think we know the way to do it.'
Meanwhile, Darren does not confine all of his energy to the University. He is also something of a fitness fanatic. In the past he has raced triathlons, marathons and fell races at a high level, and still holds ambitions to complete an Ironman triathlon and to swim Loch Lomond.
Most serious of all he wants to get back into his old habit of beating Dr Neil Broderick on their regular runs around the New Forest. 'It's such an amazing place and we're very lucky to have it on our doorstep,' he says. Of course, now I tend to find it's at its best when we're running towards the pub! And especially when Australia hasn't managed to keep up.'
Source: University of Southampton
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