Understanding the Fundamentals of Perovskites and Perovskitoids

Three- and two-dimensional (3D and 2D) halide perovskites are a broad class of organic-inorganic compounds that, over the past decade, have emerged as exceptional semiconducting materials due to their superior carrier lifetimes and structural versatility. Clearly, a deeper understanding of the role of Pb2+, and Sn2+, the role of organic spacers on the structure, properties, and performance of these devices is now essential. Perovskitoids are a separate class related to perovskites and have emerged as having broad structural and compositional diversity that is even greater than that of perovskites. Recent insights are shedding light on the types of organic spacer cations that can effectively stabilize various structures. We hypothesized that perovskitoids, with their robust organic-inorganic networks, could suppress ion migration in solar cells and improve both stability and performance. By exploring a set of perovskitoids of varying dimensionality, we found that cation migration within perovskitoid-perovskite heterostructures was effectively suppressed, leading to improved long-term stability. Increasing perovskitoid dimensionality enhances charge transport, octahedral connectivity, and out-of-plane orientation. The 2D perovskitoids (Organic cation) 8Pb7I22 provide efficient surface passivation and enable uniform large-area films, resulting in perovskite solar cells with a certified power conversion efficiency of 24.6% (Nature, 2024, 633, 359–364). This presentation will explore current knowledge of structure-property relationships and provide guidelines for selecting and incorporating organic spacers into crystalline materials and optoelectronic devices