Quantum dots could turn windows into solar panels

Ars Technica : Although solar panels can generate a large amount of carbon-free electricity, installing them in existing buildings is expensive. Incorporating them into windows and other parts of buildings would make solar energy much more affordable. However, photovoltaic cells not only block the view but also absorb a certain amount of the incoming light and cause the light that does enter the building to be tinted. A new alternative uses a transparent polymer that can be embedded in the window or applied as a coating. The polymer includes a diffuse cloud of quantum dots made of copper, indium, and selenium. The dots absorb light across the spectrum and reemit it at a specific IR wavelength, which the polymer then guides to the edge of the window glass. From there, the light is fed into a silicon photovoltaic device, which very efficiently absorbs it. Filtering out only 20% of the incoming sunlight, the device can convert just over 3% of it to electricity. Although the new material cannot harvest as much sunlight as regular solar panels, the giant walls of glass on a skyscraper could still produce a fair amount of electricity for relatively low cost.