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Date of Award
Aaron S. Rury
The research projects in this dissertation focused on understanding the light emission and structure of hybrid organic inorganic hybrid perovskites. There remains a need to develop novel synthetic approaches to synthesize self-assembled hybrid organic-inorganic nanostructures to enable solution processed lighting technologies. Bulk of the approachescurrently employed in making light emitting diodes (LEDs) for lighting applications involves complex fabrication techniques. Hence, we investigated the light emission properties of 2D hybrid organic inorganic lighting materials as potential materials for lighting applications. In Chapter 2, we employed a solvothermal approach to synthesize so called self-assembled quantum wells (SAQWs) that emit narrow light centered at 532 nm. This light emission is useful in single colored LED applications. Additionally, our synthetic approach allows us to introduce defects into these SAQWs which gives rise to broadband emission that spans about 300 nm. This broadband emission is potentially useful in near-infrared and surveillance applications. We employed X-ray structural characterization, THz and Raman spectroscopy to propose that charged defects give rise to the reported broadband emission. In Chapter 3, We employed Raman spectroscopy to investigate dynamical structural interactions in SAQWs using ammonium bending vibrations as probes. We employed a theory that we developed, to propose that the structural dynamics in these class of materials depend on the organic cation spacer molecule. Our theoretical studies allowed us to map out vibrations that may play a role in light emission properties that we discussed in Chapter 2. In Chapter 4, we reported the control of light emission in SAQWs. We reported a layered, synthetic approach which allows us to synthesize various analogues of self-assembled Pb-halide perovskites. Specifically, we can control the appearance of broadband light emission in these self-assembled materials. X-ray diffraction and electron microscopy revealed that the morphologies of the self-assembled materials differ in ways that correlate with different light emission properties and crystal morphologies. Photoelectron studies revealed that these materials are similar in composition and possess identical bonding in the bulk. Power-dependent photoluminescence studies revealed the emission is from defect sites that can act as electron donors or acceptors. Hence, we propose iodide vacancy defect mediated exciton trapping gives rise to the subgap PL we observe in these materials. The results of these studies provide useful information on the rational synthesis of various emergent luminescent self-assembled materials which could be useful in lighting applications.
Sanni, Adedayo M., "Synthetic, Mechanistic, And Structural Insights Into Defect Mediated Broadband Photoluminescence In Low Dimensional Hybrid Perovskites" (2022). Wayne State University Dissertations. 3582.