Perovskite solar cells (PSCs) hold significant promise as a renewable energy source, but their stability remains a challenge. To address this, our partners from Northwestern Engineering and Northwestern Chemistry have developed materials called perovskitoids, which are structurally similar to perovskites. These materials help reduce the migration of positively charged ions within PSCs, a key factor in improving stability, especially under high-temperature conditions. By creating a two-dimensional perovskitoid structure on the surface of three-dimensional perovskites, the team improved charge transport and achieved high efficiency and stability in large-area devices. This advance could pave the way for the large-scale application of perovskite-based optoelectronic devices.