Optoelectronics, a technology that gives off, detects, or controls light, is used everywhere in modern electronics and includes light-emitting diodes and solar cells. Within these devices, the movement of excitons (pairs of negative electrons and positive holes) determines how well the device performs. Until now, the distance that excitons could travel in conventional optoelectronic systems was around 30-70 nanometers, and there was no way to directly image how the excitons move. Now, a team of researchers from the U.S.