Structural Phase Transition and Electrical Conductivity of the Perovskite CH3NH3Sn1-<i>x</i>Pb<i>x</i>Br3 and CsSnBr3

Abstract

Abstract A series of solid solutions, CH3NH3Sn1−xPbxBr3 (x=0–1), having cubic perovskite structures was obtained by solid-state reactions. The 119Sn Mössbauer spectra for x&amp;lt;0.4, however, indicated that the tin environment was considerably distorted from a regular octahedron at 110 K. On the other hand, a single Lorentzian spectrum having a large isomer shift was observed for x&amp;gt;0.7, suggesting the presence of a regular SnBr6 octahedra in the perovskite CH3NH3PbBr3 matrix. The high electrical conductivity of the perovskite CsSnBr3 drastically decreased upon the replacement of the cation by CH3NH3 and the central metal by Pb. This behavior suggests that both the infinite linear chain (–Br–Sn(Pb)–Br–) and its bond length have significant importance regarding electrical conductivity.