Understanding Dimensionality and Connectivity of Mixed-Cation Hybrid Perovskites
This project was directed by Dr. David B. Mitzi in the Duke University Departments of Chemistry and Mechanical Engineering and Materials Science. I participated in this study during the summer of 2024.
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Image: Partially resolved structure of a mixed-cation crystal from SCXRD data
Research Project
Perovskites are a type of semiconductor with promising applications in photovoltaics, LEDs, and photodetectors. Low dimensional hybrid perovskites in particular are useful for passivating defects in 3D perovskites, which increases their power conversion efficiency in solar cells. By adding large cation spacers between the inorganic layers in low-dimensional perovskites, one can influence the degree of distortion and therefore the bond angles and lengths which determine dimensionality. This study focuses on the dimensionality and connectivity of hybrid metal-halides with mixed organic cations.
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This project used the slow evaporation method to synthesize mixed-cation single crystals with varying ratios of organic to inorganic precursor. Once evaporated, the crystals were studied under an optical microscope to learn about the crystal morphology. Then, they underwent powder x-ray diffraction (PXRD), Pawley refinement, and single crystal x-ray diffraction (SCXRD) for phase identification. If the SCXRD showed evidence of cation mixing within a crystal phase, thin films from these crystals were spin-coated from a 0.2 M solution with DMF. These thin films underwent UV-Vis spectroscopy for optical characteristic identification.