Angle-Resolved Cathodoluminescence Polarimetry of Hybrid Perovskites

Coupling between light and matter strongly depends on the polarization of the electromagnetic field and the nature of the excitations in the material. As hybrid perovskites emerge as a promising class of materials for light-based technologies like LEDs, lasers, and photodetectors, understanding the microscopic details of how photons couple to matter is critical. While most optical studies have focused on the spectral content and quantum efficiency of emitted photons in various hybrid perovskite thin-film and nanoscale structures, few studies have explored other properties of the emitted photons such as polarization and emission angle. Here, we use angle-resolved cathodoluminescence microscopy to access the full polarization state of photons emitted from large-grain hybrid perovskite films with spatial resolution well below the optical diffraction limit. Mapping the Stokes parameters as a function of the emission angle in a thin film, we reveal the effect of a grain boundary on the degree of polarization and angle at which the photons are emitted. This exploration of angle- and polarization-resolved emission near grain boundaries provides an improved understanding of the emission properties of hybrid perovskites in thin film geometries -- a necessary investigation for subsequent engineering of subwavelength nanophotonic structures using the hybrid perovskite class of materials.