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Efficient solar cells are a step closer

Last Updated: Friday, June 20, 2014 - 22:21

Washington: The more light a solar panel`s active elements absorb, the more power it produces. So, researchers have now replaced a two-step process for producing black silicon - highly efficient materials that reflect almost no light - with one.

Black silicon lets maximum amount of sunlight reach a solar cell. It is simply silicon with a highly textured surface of nanoscale spikes or pores that are smaller than the wavelength of light.

The texture allows efficient collection of light from any angle - from sunrise to sunset.
Andrew Barron and Yen-Tien Lu from Rice University in the US replaced a two-step process that involved metal deposition and electroless chemical etching with a single step process that works at room temperature.

The chemical stew that made it possible was a mix of copper nitrate, phosphorous acid, hydrogen fluoride and water.

When applied to a silicon wafer, the phosphorous acid reduces the copper ions to copper nanoparticles.
The nanoparticles attract electrons from the silicon wafer`s surface, oxidising it and allowing hydrogen fluoride to burn inverted pyramid-shaped nanopores into the silicon.

Fine-tuning the process resulted in a black silicon layer with pores as small as 590 nanometres (billionths of a metre) that let through more than 99 percent of light.

By comparison, a clean, un-etched silicon wafer reflects nearly 100 percent of light.

The findings appeared in Journal of Materials Chemistry.

First Published: Friday, June 20, 2014 - 22:21
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