Air-Stable Direct Bandgap Perovskite Semiconductors: All-Inorganic Tin-Based Heteroleptic Halides AxSnClyIz (A = Cs, Rb)

Semiconducting halide perovskites are a class of materials with exciting photoelectronic properties. Compared to the widely studied hybrid organic–inorganic perovskites, the all-inorganic derivatives are less well understood even as they promise high inherent stability. Currently, such materials are limited due to the fact that there is a very narrow choice of inorganic cations that can stabilize the desirable perovskite structure. Herein we report on the synthesis and characterization of novel all-inorganic tin-based perovskites and perovskitoids that can be stabilized by the heteroleptic coordination of chloride and iodide anions, Cs 2 SnCl 2 I 2 ( 1 ) and Cs 2.38 Rb 1.62 Sn 3 Cl 8 I 2 ( 2 ), consist of two-dimensional (2D) layers of [SnCl 4 I 2 ] 4– octahedra with different connectivity modes. Compound 1 is an n = 1 Ruddlesden–Popper type perovskite adopting the tetragonal archetype s…