Chemistry, Department of


First Advisor

Yinsheng Guo

Date of this Version

Spring 5-8-2023

Document Type



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of the Requirements For the Degree of Master of Science, Major: Chemistry, Under the Supervision of Professor Yinsheng Guo. Lincoln, Nebraska: May, 2023

Copyright © 2023 Temban Acha Billy


In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr3-xIx crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission peaks in their PL spectra. Interestingly, MAPbBr0.06I2.94 exhibited a reversible transformation showing color shift between black and orange when held at cold temperature and room temperature, respectively. Additionally, the kinetics of the reversible color shift were quantified by dissecting the RGB color of time lapse images into its components red, blue, and green channels. These results show that the forward transformation kinetics is about 10-fold slower than the reverse transformation.

Keywords: Metal-halide perovskite, halide exchange, kinetics, Raman scattering, Photoluminescence, and time lapse imaging.

Advisor: Yinsheng Guo