Hybrid Iodide Perovskites of Divalent Alkaline Earth and Lanthanide Elements

Hybrid halide perovskites AM^IIX₃ (A = ammonium cation, M^II = divalent cation, X = Cl, Br, I) have been extensively studied but have only previously been reported for the divalent carbon group elements Ge, Sn, and Pb. While they have displayed an impressive range of optoelectronic properties, the instability of Ge^II and Sn^II and the toxicity of Pb have stimulated significant interest in finding alternatives to these carbon group-based perovskites. Here, we describe the low-temperature solid-state synthesis of five new hybrid iodide perovskites centered around divalent alkaline earth and lanthanide elements, with the general formula AM^III₃ (A = methylammonium, MA; M^II = Sr, Sm, Eu, and A = formamidinium, FA; M^II = Sr, Eu). Structural, calorimetric, optical, photoluminescence, and magnetic properties of these materials are reported.