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‘Light-harvesting and electricity generation functions of a solar cell’
The team at the Southampton University School of Engineering Sciences was awarded Applied Research grant funding from the Carbon Trust to fund a project looking to lower the cost of solar cells by reducing the amount of crystalline silicon used and prove the concept for photosensitised crystalline silicon solar cells.
Summary
Creating energy from the sun is an idea that has developed significantly over the last 50 years. However, the high costof electricity generation by solar cells is holding back its development and preventing its adoption at scale. Theteam at Southampton University used a Carbon Trust Applied Research grant to try to lower the cost of solar cells by reducing the amount of crystalline silicon required. Success would be establishing the proof of concept for a photosensitised crystalline silicon solar cell.
At the conclusion of the two-year study, the team had succeeded in separating the light-harvesting and electricity generation functions of solar cells, as well as improving the quantum efficiency of prototype cells. They are now seekingfunding to support the development of a commercial prototype.
Project details
Fifty years ago, the photovoltaic industry largely consisted of tiny electrical supplies for space satellites. Today it is much more developed and, in 2005 alone, some 10 square kilometres of solar cells were produced.
 If we are to create a low carbon economy in the UK, it is essential that renewable energy sources, like solar, are adopted on a wide scale. However, the high cost of generating electricity using solar cells has inhibited its growth — current costs are around four euros per watt. A new approach was needed in order to bring down these costs and help make solar affordable for the mass market.
The team at the Southampton University School of Engineering Sciences was awarded Applied Research grant funding from the Carbon Trust to fund a project looking to lower the cost of solar cells by reducing the amount of crystalline silicon used and prove the concept for photosensitised crystalline silicon solar cells. This area of research is important as cost reduction will only be possible once new materials are in place to reduce the amount of crystalline silicon currently needed to make a solar cell. At present, more than 95% of the material in crystalline solar cells is used for light absorption rather than generating electricity.
A key success of the project was separating the lightharvesting and electricity generation functions of a solar cell. Building on this, the team at Southampton was able to prepare a laboratory exemplar of a hybrid solar cell. This combines the high optical absorption of dye molecules with the efficient electronic properties of crystalline silicon to create a solar cell with potentially a far lower capital cost than usual. The cell structure is highly efficient and requires less bulk silicon and also silicon of a lower quality than that used in conventional solar cells. Another output of the project was the characterisation of the solar cell, resulting in an improvement in the quantum efficiency of the prototype cells when compared with control samples.
Dr Tom Markvart, Southampton University, commented: "Carbon Trust funding has enabled us to take a key step in the project, and transform an idea into a working solar cell. Having established the feasibility of the concept, we are now working to improve the electrical and optical parameters of the device and develop a commercial prototype."
Moving forward, the team are looking at other novel material concepts and investigating surface passivation effects to enhance the energy collection and increase the overall efficiency of the new solar cell. Photonic structures will be used to improve the capture of the incident light and develop a new form of light management within the light-harvesting structure.
As with any project funded by a Carbon Trust Applied Research grant, the potential of the technology for commercialisation was an important factor. Now that the initial stage of the project is complete, the team are seeking funding for a commercial prototype.
For more information on Applied Research grants and all contact details, please visit our website at www.carbontrust.co.uk/appliedresearch
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