Large dynamic scissoring mode displacements coupled to band gap opening in the cubic phase of the methylammonium lead halide perovskites.

Hybrid perovskites are a rapidly growing research area, having reached photovoltaic power conversion efficiencies of over 25%. There is a increasing consensus that the structures of these materials, and hence their electronic structures, cannot be understood purely from the time and space averaged crystal structures observable by conventional methods. We apply a symmetry-motivated analysis method to analyse x-ray pair distribution function data of the cubic phases of the hybrid perovskites MAPb(= I, Br, Cl).

A powder XRD, solid state NMR and calorimetric study of the phase evolution in mechanochemically synthesized dual cation (Cs(CHNH))PbX lead halide perovskite systems.

Methylammonium (MA) lead halide perovskites (MAPbX) have been widely investigated for photovoltaic applications, with the addition of Cs improving structural and thermal stability. This study reports the complete A site miscibility of Cs and MA cations in the lead chloride and lead bromide perovskites with nominal stoichiometric formulae (CsMA)Pb(Cl/Br) ( = 0, 0.13, 0.

Symmetry-adapted pair distribution function analysis (SAPA): a novel approach to evaluating lattice dynamics and local distortions from total scattering data.

A novel symmetry-adapted pair distribution function analysis (SAPA) method for extracting information on local distortions from pair distribution function data is introduced. The implementation of SAPA is demonstrated in the software using the freely available online software , and scripts for converting the output from to a SAPA input file for are provided. Finally, two examples are provided to show how SAPA can evaluate the nature of both dynamic distortions in ScF and the distortions which act as an order parameter for the phase transitions in BaTiO.