A team of engineers from Stanford University in the US has successfully managed to improve the performance of solar PV materials by using a nanomaterial called nanocrystalline silicon, tiny spheres of which have been used by the scientists to improve the light absorption of solar panels.
The process works on the same basis as the acoustics in the famous ‘Whispering Gallery’ in the US Capitol building.
The process involves creating tiny balls of silica and then coating them with silicon to produce lightweight spheres of silicon. They then etch away the silicon centre using hydrochloric acid.
The outer shell prevents the light from escaping after it is absorbed allowing it to circulate freely within the sphere. The longer the sphere can keep the light trapped within it, the better the absorption rate will be.
The material is more cost-efficient than existing PV material as it reduces both the amount of material needed for light absorption and the amount of time spent in manufacturing the material. In fact it uses one-twentieth the amount of crystalline silicon as conventional PV materials.
Three layers of silicon represents an absorption rate of 75 percent while even a single layer is more efficient than existing material.
Furthermore, the silicon spheres can absorb light from different angles, allowing panels to absorb more light from a variety of angles relative to the position of the sun in the sky. This could help in situations where achieving the optimal angle of the sun is not always possible.
Shanhui Fan, an Associate Professor of Electrical Engineering at Stanford, said “Nanocrystalline-silicon is a great photovoltaic material. It has a high electrical efficiency and is durable in the harsh sun. Both have been challenges for other types of thin solar films.”
Yan Yao, a post-doctoral researcher said that the material could also be used for other applications such as solar fuels and photo-detectors.
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