Structural and Excited State Dynamics in Hybrid Halide Perovskites

During the last decade perovskite materials have rapidly emerged, and are currently among the most promising candidates as materials for solar cells and other opto-electronic applications. Although our knowledge related to these materials has advanced rapidly in last few years there are still many unknown aspects and many challenges remain. These challenges include a solid understanding of the relation between the composition of the materials and their structural and the photophysical processes that occur on charge excitation. In addition, there are many challenges related to the synthesis of pure-phase, defect free materials, the stability in presence of oxygen and water, and the replacement of toxic elements such as lead. In his thesis we try to shine a light on some of these unknown aspects using a combination of computational techniques such as molecular dynamics simulations and experimental techniques measuring photoluminescence. Using molecular dynamics simulations, we study the relation between the composition of the material and the static and dynamic structural properties of the individual parts of the structures. This gives insight into the effect of reduced dimensionality or introduction of aromatic molecules has on the structure. In addition, this also gives new insight in the origin of the low temperature phase transition that occurs in some perovskite materials. Experimentally we look at non-radiative pathways in perovskite nanoplatelets and how we can overcome them. Ultimately, the results presented in this thesis give some new design guidelines for perovskite materials to optimize their properties for specific applications.