Date of Award

Fall 1-1-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemical and Environmental Engineering (ENAS)

First Advisor

Guo, Peijun

Abstract

Metal halide perovskites (MHPs) have emerged as a versatile class of semiconductors with exceptional optoelectronic properties, yet their performance is intricately linked to their structural, dynamical, and photophysical characteristics. This dissertation presents a comprehensive investigation of MHPs—spanning three-dimensional, low-dimensional, and lead-free double perovskite compositions—using advanced spectroscopic techniques from the mid-infrared to X-rays. Steady-state optical spectroscopies are employed to probe ground-state properties and structure–property relationships, with emphasis on chiral 2D hybrid perovskites. A reflection-based methodology is developed to determine the intrinsic circular-polarization-dependent complex refractive index of single crystals, enabling quantitative separation of circular dichroism and birefringence. The formation of distinct spherulitic morphologies is further elucidated through correlative micro-reflectance mapping and synchrotron-based X-ray nanoprobes, revealing the link between mesoscale growth patterns and octahedral tilting. Time-resolved spectroscopies uncover the interplay between excitonic dynamics, thermal transport, and lattice phase transitions. Ultrafast mid-infrared pump–probe measurements reveal both rapid excitonic responses and slower photothermal effects, which enables precise extraction of thermal conductivities. Photothermally induced phase transition kinetics are systematically mapped as a function of temperature, fluence, dimensionality, and substrate. Overall, these studies advance both the experimental methodology and fundamental understanding of MHPs photophysics, offering guiding principles for the rational design of stable, efficient perovskite-based optoelectronic devices.

Download

Share

COinS