Room‐Temperature Formation of Highly Crystalline Multication Perovskites for Efficient, Low‐Cost Solar Cells

A room-temperature perovskite material yielding a power conversion efficiency of 18.1% (stabilized at 17.7%) is demonstrated by judicious selection of cations. Both cesium and methylammonium are necessary for room-temperature formamidinium-based perovskite to obtain the photoactive crystalline perovskite phase and high-quality crystals. This room-temperature-made perovskite material shows great potential for low-cost, large-scale manufacturing such as roll-to-roll processing. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.