In the 1970s, researchers were working to develop a window that could absorb light and convert it into electricity. The small piece of bright red plastic that Dr Erik van der Kolk has in his office at the Reactor Institute Delft is a souvenir of that time. Al-though a window with such a coating absorbs light, nobody wants red windows.
OCT-13-022: Tm2+ luminescent materials for solar-ray conversion devices
Inventor: Dr. Erik van der Kolk
For this reason, the electricity window was at a dead end for a long time. That was until two years ago, when van der Kolk and a graduating student started searching for another coating – a luminescent material with a less disturbing colour that would convert light into electricity. The researchers found this material in thulium-halides. This is now a black powder in van der Kolk’s lab.
The more thickly this powder is applied to the glass, the more electricity will be generated by the solar cells at the edges of the window. Although this technique does not yield the same capacity as the average solar panel does, it can be used as a window. According to van der Kolk, there are 5000 square metres of windows in Europe alone.
‘If we were to replace even a small portion of them with electricity windows, we could have a major impact.’ The researcher notes that potential customers have reacted enthusiastically. It will take several more years of research to demonstrate how thulium-halide can be applied to windows as a coating without scattering incoming light, however. At that point, he thinks that he will have a prototype and be able to find a commercial party to produce and sell the product.