Perovskites materials are promising candidates for next generation solar cells. However, their use is still limited by their instability within ambient conditions. Instead of absorbing all visible light and appearing black, some of these super materials preferentially form another structure which is yellow. Since only the black form is optically active, the current challenge is achieving stable black perovskites thin films suitable for real world optoelectronic devices. An international team of scientists, led by a group from KU Leuven in Belgium, have shone a light on this problem developing a new method to stabilize the black form introducing strain into the perovskite thin film using the glass substrate on which it sits. Synchrotron-based techniques at the ALBA Synchrotron and the European Synchrotron Radiation Facility were crucial for obtaining these results, published today in Science.