A three-dimensional lead iodide perovskite analog featuring hydrogen-bonded dual monovalent cations

Three-dimensional (3D) halide perovskites have attracted considerable research interest, yet the selection of A-site cations is restricted by the Goldschmidt tolerance factor. To accommodate cations beyond this acceptable range, novel 3D perovskite analog structures with edge- and face-sharing motifs have been developed. Until now, these structures have been limited to divalent cations due to significant electrostatic repulsion when incorporating two monovalent cations. Herein, we employ a supramolecular synthon mechanism to address the issue and an effective hydrogen-bonding pattern is achieved in a novel 3D lead iodide hybrid perovskite, (ammonium)(morpholinium)Pb₂I₆ (1). The inorganic framework of 1 consists of two edge-shared [PbI₆] octahedra connected via corner-sharing, thus forming a continuous 3D network. Structural analysis indicates that the spatial separation of N atoms and the existence of N-H⋯O hydrogen bonds effectively eliminate electrostatic repulsion. This work has demonstrated the potential to mitigate constraints of cation selection on 3D frameworks and could spur the development of novel 3D perovskite materials and related fields.