Wong, CathyCrawford, Michael2022-10-262022-10-26https://hdl.handle.net/1794/27780Nanocrystals (NCs) of mixed-halide perovskite materials offer great potential for solar cells and light-emitting devices owing to their unusual defect tolerance and the tunability of their bandgap via size and halide composition. However, widespread adoption of these mixed-halide perovskite materials is prevented by bandgap instability due to segregation of the halides upon exposure to light or electrical current. This segregation creates regions with a narrower bandgap than the well-mixed phase, redshifting the emission spectrum. In this work I describe efforts to prevent this process by chemical treatment of methylammonium lead iodide-bromide (MAPbIxBr3−x) NCs using a mixture of small, stronglybinding ligands. I use transient absorption (TA) spectroscopy to collect dynamics information during halide segregation, informing a computational model used to extract mechanistic information about the halide segregation process. Using this model, I determine that the observed spectroscopic trends are best explained by iodide anions preferentially segregating into a region within the NC, rather than directly toward the NC surface. The mechanistic insight provided by this work will contribute to future approaches to stabilizing the bandgap in mixed-halide perovskite NCs.en-USAll Rights Reserved.Core-Shell HeterostructureGlobal Fitting AnalysisHalide SegregationNanocrystalPerovskiteTransient AbsorptionElectronic Thesis or Dissertation