CRYSTALLOGRAPHY OF TITANIUM BASED ORGANIC-INORGANIC HALIDE PEROVSKITES

Author

Kyle Jeffrey Heller, Southern Illinois University CarbondaleFollow

Date of Award

12-1-2020

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Mondal, Kanchan

Abstract

Kyle Heller, for the Master of Science degree in Mechanical Engineering, presented on October 2020, at Southern Illinois University Carbondale.MAJOR PROFESSOR: Dr. Kanchan Mondal Using powder X-ray diffraction, a material can have its crystalline structure identified. Powder X-ray diffraction alone is not enough if a material is unknown. Usually the exact chemical formula of the material is known, or a secondary analytical method is used to extract additional data in order to analyze the crystalline structure using Bragg’s law and the interplanar relationships. Secondary analytical methods are not as easy or inexpensive though. Generic values could be placed into the more basic structure types to obtain a rough idea of potential crystal types including space groups for the material based on its diffraction peaks. However, with a material that has an unknown spacing between its atoms (d-spacing) this is harder to implement. Thus, the use of a secondary software was employed to further analyze the possibilities. In this thesis, the software used for data extraction and refining were Expo 2014 and CrystalMaker X paired with CrystalDiffract and the final visualization was achieved using Endeavor. Two different titanium based organic inorganic halide perovskites (Dye 3 and Dye 4) prepared at different temperatures were evaluated to identify the crystallographic structure using only x-ray data available. The crystal parameters were calculated, and potential unit cells were visualized. Both the materials were found to be 4 (ABX3) type perovskites. The organic component for Dye 3 was methyl ammonium ion and that of Dye 4 was formamidinium ion. These perovskites have shown potential for use as sensitizers in visible light photovoltaic cells. It was concluded that Dye 4 was orthorhombic with a space grouping of C m c a (space group 64). The associated values were a = b =7.94 Å and c =11.55 Å. Dye 3 was also found to be orthorhombic with space grouping of P c c n (space group 56) being a better fit than C m c a. The associated values were a=b=16 Å and c=11 Å.