Researchers at University of Tsukuba have used electron spin resonance technology to observe the state and movement of the charge inside Ruddlesden-Popper tin -based perovskite solar cells, an emerging technology for next-generation solar cells. They have discovered a mechanism that improves the performance of these cells compared with conventional three-dimensional tin-based perovskite solar cells. Their findings signal a great leap forward in the development of high-efficiency, long-lasting solar cells.