Science classifies light by wavelength rather than colour. As such, colours such as yellow and red correspond to wavelengths of around 570 and 620 nm, respectively. Unlike visible colours, wavelength is also applicable to describe radiation invisible to the human eye. Radiation with wavelengths longer than that of red light is called infrared light. Infrared technology is very relevant for applications where visible light cannot be used, such as thermal imaging, counterfeit detection in the pharmaceutical industry, or telecommunication.
The problem is that in the infrared, suitable materials for light sources and light detection are scarce, expensive and often made of toxic elements such as Pb, Cd or Hg. The Physics and Chemistry of Nanostructures group at Ghent University develops colloidal semiconductor nanocrystals, which could offer a solution here. Colloidal nanocrystals are so small that they can be suspended in liquids to form printable semiconductors that can emit or detect light. This makes these materials very affordable, since they may be used to print light detectors. Here, we propose to develop such a photodetector based on nanocrystals made of so-called III-V semiconductors that can become an alternative to the currently used infrared detectors. The research hypothesis is that controlling the surface of these nanocrystallites is the key to demonstrating a working infrared detector, which may provide access to unavailable or overly expensive technologies.