The search for interactions of dark matter particles (WIMPs) with ordinary matter is carried out with large underground detectors, with currently the most promising detection technology based on the use of a large mass of liquid argon or xenon as the detector medium. Efficient collection and detection of light from multi-tonne detectors poses challenges and motivates dedicated R&D on optical materials, including wavelength shifters, as well as on photosensors. Such work at AstroCeNT, either in the context of the Global Argon Dark Matter Collaboration, or general R&D applicable also to neutrino detectors, will be presented, together with a brief overview of the field.