Through the combined efforts of researchers from the University of Minnesota and University of Milano-Bicocca, we may soon be seeing windows that can do more than just let natural daylight in. According to the research which was recently published in the journal “Nature Photonics“, with the addition of silicon nanoparticles, ordinary windows can be transformed into photovoltaic windows capable of harvesting solar energy and converting it into electrical energy.
The technique involves embedding silicon nanoparticles into what are referred to as luminescent solar concentrators (LSCs). When light shines through these LSCs, light’s useful frequencies get trapped inside and are directed to the edges where solar cells can be placed strategically to capture the energy.
The use of silicon makes this technique more promising than others for several reasons. For starters, silicon is naturally abundant in our environment. And even if it wasn’t, it still won’t be a problem because the amount needed is quite small. Second, silicone is non-toxic, whereas other nanostructures currently being used contain some toxic elements like lead, cadmium or even iridium which is already widely being used for other technologies. Third, silicon can absorb different wavelengths of light, which makes it more efficient at absorbing energy. Lastly, silicon nanoparticles are nearly invisible. That means they won’t have any impact on a building’s appearance. And for buildings in urban areas, this is of crucial importance.
In its conventional form, silicon is in fact bulky and does not even emit light. To come up with nanoparticles, a high-tech process involving the use of a plasma reactor turns naturally bulky silicon crystals into powder-like form. By shrinking it down to this nanometer size, the researchers were able to alter silicon’s properties, making it an ‘efficient light emitter’ that doesn’t absorb its own radiance or luminescence. Supposedly, this feature is what makes the silicon nanoparticles ideal for LSC applications.
The process of silicon nanoparticle creation was invented at the University of Minnesota more than a decade ago by Uwe Kortshagen, one of the lead authors of the study. On the other side of the world was University of Milano-Bicocca physics professor Sergio Brovelli, who also happened to be co-founder of a company that specializes in industrializing LSCs for photovoltaic windows.
When Kortshagen and Brovelli met, the partnership that integrated their separate expertise was born. According to the team, the silicon nanoparticles’ optical features, combined with their near-ideal compatibility with the industrial production of polymer LSCs, will make it feasible to create efficient photovoltaic windows that aren’t just inexpensive to produce, but are capable of trapping over 5% of solar energy.
In a report by Phy.Org, Kortshagen was quoted as saying: “We had the expertise in making the silicon nanoparticles and our partners in Milano had expertise in fabricating the luminescent concentrators. When it all came together, we knew we had something special.”