Western Mail Profiles: Dr Jeff Kettle

‘Harness sun’s power to get our electricity’

Dr Jeff Kettle is a lecturer in the School of Electronic Engineering at Bangor University. He is investigating new forms of solar panels and lighting.

IF you look at the landscape of a city at night, the number of lights you see demonstrates the amount of electricity we use on lighting.

In the UK about 25% of electricity generation goes on lighting and if we could reduce the electricity these lights use, we can reduce our electricity consumption.

Further questions also remain how to power such cities in the future. One possibility is to exploit the sun’s energy using solar panels. The sun generates about 1050kw hours per meter squared every year in Wales. If just a proportion of light from the sun could be converted into electricity, we could meet all our electricity demands in Wales.

What links both lighting and solar energy generation is the underlying physics of the way that light interacts with molecules.

My research is about controlling this interaction in electronic devices such as Light Emitting diodes (LEDs) and solar cells. Solar cells take light or “photons” and convert it to another type of energy called excitons (“an excited electron”).

LEDs take electrons and convert them to photons. Most of the materials used in devices such as these are made of crystalline semiconductors such as silicon.

Silicon is expensive to produce. To manufacture a single crystal silicon solar cell, we need to melt sand and carefully control the cooling to produce a silicon crystal, which is an energy intensive procedure.

If you take approximately 20% of the total electricity produced by a silicon solar cell in its 20 year life, that is equivalent to the energy needed to manufacture the cell in the first place.

In my research, we are developing the technology to move away from this crystalline material and use an excitonic material. Excitonic materials come in many forms. My focus is on organic semiconductors. The organic semiconductor materials we use are based on polymers and dyes, which are all carbon-based and don’t use any toxic or rare materials.

If we can use these molecular materials in LEDs and solar cells, then it is possible to make a device very cheaply and over a large area, as the great advantage of these materials is their compatibility with printed manufacturing.

This would enable us to fabricate solar cells and LEDs in the same manner that packaging, newspapers and wallpaper is made, using roll-to-roll printed manufacturing.

In this case, a flexible substrate, such as a plastic, is rolled down a production line and the LED or solar cell can be simply printed on top of it. If these materials can be made close to the efficiency of silicon, then due to the lower cost, they will gain a significant market share.

When you look outside your window at a tree, the leaves are using photosynthesis to generate energy; this is a natural example of solar energy conversion using molecular materials. In electronics, we’re a long way behind replicating photosynthesis. But hopefully, my research takes us a few steps towards that.

To contact Jeff email j.kettle@bangor.ac.uk

This article first  appeared in the Western Mail‘s Health Wales supplement on 15th October, 2012, as part of the Welsh Crucible series of research profiles.