MAPbBr2.3I0.7 | Pb(II)-System with Cubic Perovskite Structure

Overview

In the APbX3 system (A = monovalent cation, X = Cl, Br, I), the perovskite structure is so far only known in high-temperature modifications of the type CsPbX3 [1, 2]. In contrast, the Sn(II) analogue CsSnBr3 [3-5] crystallizes in the cubic perovskite lattice even under normal conditions. Presumably, the size of the Cs+ cation is not sufficient to fill the space available to it in a Pb(II) perovskite structure so that the crystal field energy at room temperature forces the Pb(II) into octahedral symmetry. Accordingly, the transformation temperature from CsPbCl3 to CsPbI3 increases sharply.