Structural Phase Transition and Electrical Conductivity of the Perovskite CH3NH3Sn1-xPbxBr3 and CsSnBr3

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<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>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.

Intriguing Optoelectronic Properties of Metal Halide Perovskites

“…99 This effect was observed by Yamada et al in the decreasing conductivity of the series CsSnBr 3 , CH 3 NH 3 SnBr 3 , CH 3 NH 3 Sn 1−x Pb x Br 3 , and CH 3 NH 3 PbBr 3 . 316 Hao et al observed the same effect in CH 3 NH 3 Sn 1−x Pb x I 3 alloys where the conductivity is at a maximum in pure CH 3 NH 3 SnI 3 . In CH 3 NH 3 SnI 3 , the Sn−ISn bond angles are close to 180°, but this angle decreases with increasing Pb as the B−IB bond distorts, leading to a decrease in conductivity ( Figure 37).…”

“…230,315 The slight uptick in k 2 upon transition to the cubic phase may stem from an increase of the BXB bond angle in the high-temperature phase (section 2). This type of structural modification has been linked to increased mobility in MHPs (section 5.1), 99,316,317 and, as expected from Langevin theory, k 2 should increase. However, the mobility measured by TRTS does not show appreciable increase in the cubic phase.…”

Optical properties and ab initio study on the hybrid organic–inorganic material [(CH3)2NH2]3[BiI6]

“…Perovskite-like based hybrids can be synthesized with simple and cheap techniques thanks to their self assembled character [5]. The desired structural and electronic properties [6,7] can be engineered through a suitable choice of both the inorganic cage and the cation. Therefore, the dimensionality can be used as a further degree of freedom for tuning the material properties.…”

Control of organic–inorganic halide perovskites in solid-state solar cells: a perspective

“…1). The crystal structures of perovskites can be transited between cubic, tetragonal and orthorhombic depending on the temperature [3,4]. Many well-known perovskites are fully inorganic, e.g., BaTiO 3 [5], BiFeO 3 [6] or SrTiO 3 [7], and they are featured by piezoelectric or ferroelectric properties and abnormal photovoltaic effect [8][9][10].…”