Since they were first developed in the 1950s, photovoltaic cells — which convert the energy in sunlight to electricity — have usually been made of silicon. But these are expensive to produce, as the silicon needs to be extremely pure, making it difficult for solar power to compete with traditional ways of generating electricity.
Eric W. McFarland and Jing Tang at the University of California, United States, have now created a device that could change this situation. Instead of silicon, their cell uses a layer of brightly coloured dye molecules on a thin gold film to harness the light — similar to the way in which plants harvest light through photosynthesis.
"This alternative approach to photovoltaic energy conversion might provide the basis for durable low-cost solar cells using a variety of materials," they say.
Dye-based cells are not new. But so far they have struggled to achieve efficiencies that are competitive with current solar energy techniques. The efficiency of McFarland and Tang's cell is still relatively low (less than 1 per cent), but it does offer promise for the future.
"What is remarkable… is their finding that about 10 per cent of the photons absorbed by the dye layer actually generate electric current," says Michael Gratzel of the Swiss Institute of Photonics and Interfaces, in a related news and views article.
Many developing countries are already investigating the use of solar panels to provide electricity in remote rural areas that are inaccessible to standard grid-based electricity. The development of cheap solar devices would make more widespread implementation a viable prospect.
© SciDev.Net 2003