Date of Award

12-24-2025

Date Published

January 2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor(s)

Mathew Maye

Second Advisor

Jesse Bond

Keywords

Ion-doping;Lead-free;Nanocrystal;Perovskite;Plumbates;Quantum dots

Subject Categories

Chemistry | Physical Sciences and Mathematics

Abstract

Colloidal semiconductor nanocrystals feature unique properties like quantum confinement, tunable band gaps, and high surface-to-volume ratio; and have been proven as prominent materials in applications such as light-emitting diodes, sensors, lasers, solar cells, etc. Optoelectronic properties of semiconductor nanocrystals are highly associated with their sizes, morphologies, and compositions. Understanding the growth mechanism can lead to the ability to control the size, morphology, and composition of nanocrystals. In this thesis, growth and b-site doping of perovskite, cesium lead halide (CsPbX3), nanocrystals are discussed. Solvent effects in the growth of cesium lead bromide were first investigated from the aspect of plumbates in precursors. Plumbates play vital roles in the synthesis of CsPbBr3 since lead salts were first dissolved as plumbates in solvents with ligands. We applied optical assays and 207Pb nuclear magnetic resonance (NMR) to understand the formation of plumbates in the precursors. Characteristic absorption peaks in the UV-vis region were used to assign the species of plumbates in different solvents. Formations of plumbates in various solvents were studied as were formation constants. Room temperature and hot injection synthesis mechanism were conducted to understand the solvent effects on the CsPbBr3 growth. The dopant effect from b-site nickel doping in CsPbBr3 was next investigated. We performed the modified room temperature method to synthesize Ni-doped CsPbBr3 NCs. Photoluminescence (PL), ultraviolet–visible (UV-vis) spectroscopy, and powder X-ray diffraction (XRD) were used to investigate the optical properties and crystal structure. Magnetic susceptibility measurements were collected at various temperatures to understand the magnetic properties. In order to explore emission tunability and alternative ways of doping, a further ion exchange method was conducted. Doped sample compositions were measured by ICP-OES to confirm the dopant content. Due to the toxicity of lead, lead-free perovskite and alternative emissive materials were also explored. Blue emission metal-doped CsBr NCs were further studied. Co-/Ni-doped CsBr NCs were synthesized by a hot injection method, and the crystal structures were investigated by PXRD and HR-TEM. Optical properties were then studied by PL and UV-vis. Further time-resolved TEM observations were conducted to explore the relation between humidity and morphologies as well as potential applications.

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