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Author ORCID Identifier
https://orcid.org/0000-0001-9961-267X
AccessType
Campus-Only Access for One (1) Year
Document Type
dissertation
Degree Name
Doctor of Philosophy (PhD)
Degree Program
Chemistry
Year Degree Awarded
2024
Month Degree Awarded
February
First Advisor
Kevin R. Kittilstved
Second Advisor
Dhandapani Venkataraman
Third Advisor
Ricardo B. Metz
Fourth Advisor
Dimitrios Maroudas
Subject Categories
Inorganic Chemistry | Materials Chemistry
Abstract
Aluminum-doped ZnO nanocrystals (NCs) are a low-cost alternative to indium tin oxide due to their comparable optical and electrical properties. They are widely used as coatings in electrochromics, solar cells, light-emitting diodes, and touch-screen displays. The energetics of the conduction and valence bands in Al-doped ZnO NCs are critical determinants of their optical and electrical properties. Understanding the band potentials of Al-doped ZnO NCs is crucial for enhancing their optical and electrical properties. Chapter 2 focuses on the utilization of air-stable, delocalized electrons on the conduction band to modulate the valency of Fe dopants in Fe–Al codoped ZnO NCs by varying Al concentration. The precise control over the Al doping concentration enabled the reduction of substitutional Fe3+ dopants fully or to a certain extent to achieve mixed-valency Fe dopants, as confirmed by electron paramagnetic resonance spectroscopy measurements. Chapter 3 investigates the interplay between Fe and Al dopants to elaborate on the dopant incorporation kinetics using the etching-regrowth-doping method. Results showed that the incorporation of Fe dopants is preferred during the growth step due to the better ionic radius match between Fe and Zn. This led to relatively higher Al monomer concentrations for the regrowth step of the reaction, facilitating increased Al incorporation. However, this increased Al incorporation did not result in an increase in the carrier density. Varying Al concentration and the type of co-dopant from Al to In or Ga were effective strategies to reduce the substitutional Fe dopant while the interstitial Fe dopant remained in the 3+ oxidation state. This observation led to investigating the reduction potentials in Al-doped ZnO NCs in solution using an electron reservoir, discussed in Chapter 4. The long-term colloidal stability and solution processability of colloidal nanocrystals are strongly dictated by the identity of their surface capping ligands. Chapter 5 focuses on a rapid, single-step synthesis of methoxy(triethyleneoxy-propyl) trimethoxysilane capped ZnO NCs, which exhibit high colloidal stability and a wide range of solvent compatibility compared to non-silane-capped colloidal ZnO NCs. Surface functionalization is achieved by silanization either in a single step during the growth process or through a post-synthetic ligand exchange.
DOI
https://doi.org/10.7275/36380595
Recommended Citation
Buz, Enes, "SYNTHESIS AND CHARACTERIZATION OF ZnO NANOCRYSTALS: ALIOVALENT DOPING TO SURFACE MODIFICATION" (2024). Doctoral Dissertations. 3035.
https://doi.org/10.7275/36380595
https://scholarworks.umass.edu/dissertations_2/3035
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.