Rubidium pushes perovskite solar cells to 21.6% efficiency

30. EPFL scientists have stabilized perovskite solar cells by integrating rubidium into them. The innovation pushes power-conversion efficiency to 21.6%, ushering a new generation of perovskite solar cells. Perovskite solar cells have great potential for providing us with cost-effective solar energy. However, heat stability is an issue, and can significantly limit the solar cell's long-term efficiency, as the cell's structure can degenerate over time. A solution has been to mix perovskites with other materials, such as cesium, that can improve the cell's stability without compromising its efficiency in converting light into electrical current. Michael Grätzel's lab at EPFL has now integrated rubidium cations into perovskites, maintaining exceptional stability over 500 continuous hours in full sunlight at 85°C, while pushing power-conversion efficiency to a reported record value of 21.