- Category: Technology
11 Jul 2013
- Published on Thursday, 11 July 2013 04:46
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German researchers have developed a way to make colored solar cells from paper-thin silicon wafers.
color doesn’t really matter when we’re talking about solar panels efficiency, it does matter a little when designers or property owners are thinking about how a solar panel might contribute to the over-all aesthetics of a building or facility.
Not enough work has been done so far on combining photovoltaics and design elements to really do the term ‘customized photovoltaics’ justice,” said Kevin Füchsel, project manager at the Fraunhofer institute for Applied Optics and Precision Engineering IOF in Jena.
Mr. Füchsel, a physicist, has been focusing for the last four years on developing nanostructured solar cells suitable for mass production as part of a junior research group funded by Germany’s Federal Ministry of Education and Research.
The solar cells developed by the group use a paper thin layer of silicon as its semiconductor layer. Only a few micrometers thick, the layer absorbs the light and turns it into electricity. To enable a lot of light to reach the silicon substrate, the semiconductor layer uses an optically neutral protective barrier or insulator onto which a hundred-nanometer-thick layer of transparent conductive oxide is applied. The T.C.O. layer conducts electricity and guides as many light particles as possible to the semiconductor layer below.
“T.C.O. has a lower refractive index than silicon, so it works as an anti-reflective coating,” explained Mr. Füchsel.
The T.C.O. layer is also what enables the solar cell to be made in different colors.
“The color comes from changing the physical thickness of the transparent conductive oxide layer, or modifying its refractive index,” said Mr. Füchsel.
Simulations showed that these cells could have an efficiency of up to 20 percent. In practice, the efficiency depends on the design of the solar panels and the direction the building faces. But not every color allows for the same amount of electricity generation and there are restrictions for certain blends of red, blue and green.
The researchers are currently working on optimizing the design as well as modifying some of the materials used. They are also developing an inkjet printing process to add the T.C.O. layer. This will make manufacturing faster and allow greater degrees of flexibility in design. – EcoSeed Staff