Accounting for dynamical scattering in HRTEM FFT interpretation using electron diffraction simulations of hybrid perovskites

The hybrid organometallic perovskite CH 3 NH 3 PbI 3 has attracted significant interest due to its structural properties and potential applications in solar cells, light-emitting diodes (LEDs), and detectors. This material exhibits different crystalline phases that can vary with temperature, humidity, and the presence of the organic cation CH 3 NH 3 + , which complicates its structural characterization via transmission electron microscopy (TEM). Analysis of fast Fourier transforms (FFTs) of high-resolution TEM (HRTEM) images indicates the existence of reflections forbidden by the perovskite structure factor. In order to identify their origin, in this work, we present the electron diffraction analysis and diffraction simulation of the most stable tetragonal phase (space group I4cm) of the hybrid perovskite, aimed at identifying and analyzing the predominant characteristics in reciprocal space. The results indicate, in addition to the structure factor allowed reflections, the existence of dynamically excited forbidden reflections associated with multiple diffraction of the sample-electron beam interaction. This combined experimental and simulation approach provides a better interpretation of TEM images and a more reliable structural characterization of beam-sensitive materials under dynamical scattering conditions.