Although many have become familiar with solar power as an economical way to heat our water in geysers and light our gardens, the potential for solar power reaches far beyond this. We could potentially harvest electricity from windows using photovoltiac solar energy.
Photovoltiac solar energy is a method of converting solar energy into direct current electricity with the help of semi-conducting materials. This allows the solar-capturing material to be small and spread over surfaces in large quantities. However, while photovoltiac hardware requires light to work, the silicon panels appear black – hardly well suited for use over windows.
Enter quantum dots. Science Daily describes quantum dots as “a semiconductor nanostructure that that confines the motion of conduction band electrons”. These dots measure between 10 and 50 nanometres in diameter (about 10-5 millimetres). In a research paper published via Nature.com, entitled Highly efficient large-area colourless luminescent solar concentrators using heavy-metal-free colloidal quantum dots, the authors researched combining these two technologies to create zero energy consumption buildings.
Tech site Ars Technica reports that, although a combination of these two seems like the perfect solution to everlasting sustainable energy, the problem is that microdots aren’t used to generate electricity: “Simply absorbing the light doesn’t help generate electricity”.
The authors created quantum dots made of copper, indium and selenium, and covered them with a layer of zinc sulphide. The dots then absorb light across a broad spectrum, and re-emit light at a specific wavelength in infrared, which is absorbed by a silicon photovoltaic device. Placing these devices around the outside edge of a panel of glass would allow them to absorb solar energy.
The team concluded that, despite the energy losses, up to 3 % of the available energy was captured in 12-centimere devices. Although this does not detract from the importance of solar panels, it could significantly contribute to the overall solar potential of a building with panels of glass or windows. Source: Ars Technica