Imperial College London

A 'quantum of sol' – how nanotechnology could hold the key to a solar-powered future

Absorbing light

Imperial solar cell physicists take part in the Royal Society Summer Science Exhibition<em> - News Release</em>

Imperial College London news release

For immediate use
Tuesday 30 June 2009

A new generation of 'nano-structured' millimetre-sized solar cells that could convert the sun's energy to electricity more than twice as efficiently as current technology, is the subject of an Imperial College London exhibit called 'A Quantum of Sol' at the Royal Society Summer Science Exhibition 2009, which opens to the public today (30 June).

Visitors to the exhibit will be able to play at being solar power engineers, and use prisms to see how much electrical power can be generated by the different colours within the spectrum of light.

The exhibit is led by Dr Ned Ekins-Daukes, a researcher from the Department of Physics and the Grantham Institute for Climate Change at Imperial, who also launches the first in a series of Grantham Institute briefing papers at the exhibition today (30 June).

The 'Quantum of Sol' exhibit explains the technology behind so-called 'third generation' solar cells. These are designed on the nano-scale, which means the materials they are made of are custom-built on a scale 1000 times smaller than the size of a human hair. These third generation solar cells can capture more of the sun's energy than existing silicon solar panels because they contain different layers of material that absorb a broader spectrum of colours. Individually targeting different colours of sunlight in this way captures more of the sun's energy, creating much more efficient solar cells.


The new millimetre-sized solar cells capture more of the sun's energy than traditional solar panels

Visitors to the exhibit will be able to see this principle in action by sliding a working solar cell through light that has been split by a prism into its constituent colours, to see how each colour generates different amounts of energy.

They will also get the chance to play the role of solar power engineers, positioning small mirrors and lenses on a board to focus a beam of light onto a miniature solar cell. This is a scaled-down representation of a type of solar technology used in the desert, known as a 'concentrator power system', where swathes of mirrors or lenses are used to focus sunlight onto small but highly efficient solar cells.

Silicon solar panels, which have been around since the 1950s and are relatively cheap to produce, lose a lot of the sun's energy, and tend to operate with just 12 – 20% efficiency. The new generation of so-called 'multi- junction' solar cells has the potential to perform much better, with the current world record for efficiency standing at 41%, and Dr Ekins-Daukes predicting that 50% efficiency will be achieved within a decade.

"One of the biggest challenges for scientists working in the solar power field is finding ways of harnessing the sun's energy more efficiently," says Dr Ekins-Daukes. "Our exhibit gives people the chance to get a hands-on understanding of the research underway at Imperial and elsewhere in the world to develop new solar cells that capture the light missed by other solar panel designs."

Although using nanotechnology to build these new solar cells is expensive at present - $14 per square centimetre - a solar concentrator system collects and focuses sunlight using inexpensive mirrors. In this way, the electricity generated can become affordable. In 2007, Imperial College London spun out a company, Quantasol, which has recently developed a particularly efficient single-junction solar cell, which forms part of the exhibit.

The international efforts to improve the efficiency of this new generation of cells and the potential for the technology to become more affordable in the future are outlined Dr Ekins-Daukes' Grantham Institute for Climate Change briefing paper – copies of which will be available at the Royal Society exhibition.

Entitled 'Solar energy for heat and electricity: the potential for mitigating climate change', the briefing paper appraises the current state of play in the solar energy field, describing solar energy's potential contribution to climate mitigation goals, and outlining what needs to be done to reach these goals.

It is the first in a planned series of briefing papers that will be published by the Grantham Institute for Climate Change to provide a source of information about key issues linked with climate change science, adaptation and mitigation. Aimed at key policy- and decision-makers, the series of briefing papers is part of the Grantham Institute's mission to generate and communicate the highest quality research on climate change and to translate this research into sustainable technological, political and socio-economic responses.

Director of the Grantham Institute for Climate Change at Imperial, Professor Sir Brian Hoskins, commented: "I'm delighted that the first of our planned briefing papers is being launched at the Royal Society's Summer Science Exhibition. This event provides a great opportunity for Dr Ekins-Daukes to share his expertise in photovoltaics with young people and the general public, whilst the briefing paper's more in-depth analysis of the broader solar energy field makes it a must-read for those in business and government charged with making decisions that will affect how we get energy and heat for our homes and workplaces in the future."


For more information please contact:
Danielle Reeves, Imperial College London press office
Tel: +44 (0)20 7594 2198
Out-of-hours duty press office: +44 (0)7803 886248

Notes for editors:

1. Reporters can download an embargoed copy of the first Grantham Institute briefing paper, entitled 'Solar energy for heat and electricity: the potential for mitigating climate change' here.

2. About the Grantham Institute for Climate Change

The Grantham Institute for Climate Change is committed to driving climate change related research and translating it into real world impact. The Institute's researchers are developing both the fundamental scientific understanding of climate change, and the mitigation and adaptation responses to it. The Institute intends that this work should be directly relevant to policy and decision makers.

The Grantham Institute for Climate Change is unique among climate change research centres because it is situated at the heart of Imperial College London, one of the world's leading science, technology and medicine universities. The policy and outreach work that the Institute carries out is based on, and backed up by, the leading edge research of the College's academic staff.

The Institute has so far provided funding for 15 academic research posts and 20 PhD studentships at Imperial College London in areas including ocean modelling, carbon sequestration, flood and drought risks, novel photovoltaics, climate impacts on biodiversity, climate/health and carbon finance.

Imperial established the Grantham Institute for Climate Change in February 2007 following a £12.8 million donation over ten years from the Grantham Foundation for the Protection of the Environment.

3. About Imperial College London

Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 13,000 students and 6,000 staff of the highest international quality.

Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve health in the UK and globally, tackle climate change and develop clean and sustainable sources of energy.

4. Press preview of this exhibit and others on show: 15.00 – 17.00 on Monday 30 June - please register your interest with the Royal Society press office on 020 7451 2508.

5. General info: The Royal Society Summer Science Exhibition showcases cutting edge research in science and engineering from across the UK. It is held annually at the Royal Society, the UK's national academy of science.

The Exhibition runs from Tuesday 30 June to Saturday 4 July 2008.

The event is FREE and open to the public.

This year, 23 interactive exhibits will be on show presenting the best of UK science, engineering and technology. During the four days of the event, more than 4,000 people are expected to take up the opportunity to explore the exhibition.

The Royal Society can be found at 6-9 Carlton House Terrace, London, SW1Y 5AG. Nearest tube stations are Piccadilly Circus or Charing Cross.

6. Exhibition opening times:

Tuesday 30 June 2009: 10am - 9pm
Wednesday 1 July 2009: 10am – 5pm
Thursday 2 July 2009: 10am – 5pm
Friday 3 July 2009: 10am – 5pm
Saturday 4 July 2009: 10am – 5pm

Last entry 30 minutes before closing

Further information can be found at

7. The Royal Society is an independent academy promoting the natural and applied sciences. Founded in 1660, the Society has three roles, as the UK academy of science, as a learned Society, and as a funding agency. As we prepare for our 350th anniversary in 2010, we are working to achieve five strategic priorities, to:

• Invest in future scientific leaders and in innovation
• Influence policymaking with the best scientific advice
• Invigorate science and mathematics education
• Increase access to the best science internationally
• Inspire an interest in the joy, wonder and excitement of scientific discovery

8. Between November 2009 and November 2010, the Royal Society will be celebrating its 350th anniversary, promoting a spirit of enquiry, excitement and engagement with science. The Society will be working with organisations, across the country to raise the profile of science and bring scientific activities to a new audience. This will include:

• A unique nine-day science festival in the summer of 2010, held at the Southbank Centre in London. There will be collaborations with artists and performers, debates, broadcasting and the participation of audiences. In particular, it will include an enhanced version of the Society's annual summer science exhibition, which gives visitors the opportunity to meet the scientists and engineers at the forefront of the UK's research activities and to explore their work through interactive exhibits.
• The Local Heroes programme - the Society will be working with fifty smaller museums and galleries around the UK to celebrate their local scientific heroes, whether they are pioneers of the industrial age, geniuses that changed the way we see the world today or contemporary scientists finding solutions to today's problems.
• Public lectures, debates and discussion meetings at the Society’s premises in Carlton House Terrace.
• Publication of special editions of the Society's scientific journals and a popular book covering the unique history of science and scientific issues of the last 350 years.

More information about the anniversary year can be found at

For further information contact:
Nicola Kane
Press and Public Relations
The Royal Society, London
Tel: 020 7451 2508

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