How can the latest technology, such as solar cells, be improved? An international research team led by the University of Göttingen is helping to find answers to questions like this with a new technique. For the first time, the formation of tiny, difficult-to-detect particles—known as dark excitons—can be tracked precisely in time and space. These invisible carriers of energy will play a key role in future solar cells, LEDs and detectors. The results are published in Nature Photonics.