Manufacturing solar cells that are one thousand times thinner than conventional cells. That is the challenge the researchers have set for themselves. In order to boost the output of the cells, they have developed a new nanopatterning technique.
Even though silicon is one of the most abundant elements, the energy required to make silicon from sand is immense. It is for this reason, but also to reduce manufacturing costs, that Christophe Ballif and his team from the Photovoltaics and Thin-Film Electronics Laboratory in Neuchâtel have been working for several years on thin-film silicon solar cells that are a thousand times thinner than conventional cells.
Better light absorption
There’s just one catch: the thinner the cells, the less they absorb the rays of the sun and the less electricity they produce. So researchers are trying to trap light in the thin silicon layers to increase their absorption. Traditionally, thin layers of zinc oxide—a material that is very abundant, completely non-toxic, and that grows in the form of small pyramid-shaped crystals—are used for this purpose. These crystals scatter light efficiently into the underlying silicon layer. With such zinc oxide layers, even a new world record cell efficiency was achieved.