The great challenge of any sort of photovoltaic cell is to extract energy from as many different wavelengths as possible. Snaith made a type of perovskite that catches blue light effectively, but lets most red light through, and printed a layer of it on glass. This was stacked above a different type of perovskite, one which is effective at trapping red light.
Although blue light-specialist perovskites have been around for some time, it took Snaith's co-author Dr Giles Eperon of the University of Washington to make one suited to the red end of the spectrum. Using a combination of tin, lead, cesium, iodine, and organic materials, Eperon succeeded to the extent that his work even captures near-visible infrared light.
Besides the need to increase efficiency, the major obstacle to practical use of perovskite solar cells is that most quickly lose performance when exposed to oxygen, heat, or water. After cooking their product for four days at 100°C (212°F), Snaith and Eperon were satisfied that heat will not be a problem, and don't think oxygen will be an issue either.
The solar future touted in Nature Energy this week could be closer than even its advocates realized.