Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)
DOI: https://doi.org/10.29363/nanoge.hopv.2024.135
Publication date: 6th February 2024
Metal halide perovskites forms a very exciting material class for various opto-electronic applications. These materials form multi-crystalline films of exceptionally high quality by methods as simple as spin-coating. The soft and ionic nature of the polycrystalline perovskite films leads to highly complex material properties that can vary over time and from grain to grain. To include perovskites in commercial applications, we need to understand their optoelectronic and structural characteristics on the scale of single grains (eg nanometers). Cathodoluminescence microscopy has been used successfully in the past to study grain-to-grain variation in luminescence efficiency and has shown that surface traps not only dominate carrier trapping, but also are distributed unevenly amongst various grains.1 These detailed optical studies are often correlated to bulk film orientation and only few studies have correlated optoelectronic properties to structure at the nanoscale.2,3 We combine nanoscale characterization of optical and structural properties by correlating cathodoluminescence and electron backscatter diffraction analysis on the same location in perovskite thin films. Electron backscatter diffraction is an electron microscopy technique that gives information on the local grain orientation, grain boundaries and strain.2,4 By combining these electron microscopy-based techniques, we can learn if and how the existence of surface traps is related to specific grain orientations. On top of this, we can correlate photoluminescence quenching at grain boundaries to the relative orientation of the crystallites that make up the boundary. By pin-pointing the points of origin of processes such as electronic carrier trapping or halide segregation, we hope to further the understanding of perovskites at the nanoscale, and inform the efforts towards more effective film passivation.