Phototropic Growth of Cu₂O: Light-Directed Semiconductor Mesostructuring via Photoelectrodeposition

Author: Byrne, Sean Thomas

Year: 2027

Degree: Dissertation (Ph.D.)

Advisor: Lewis, Nathan Saul

Committee Members: See, Kimberly; Cushing, Scott K.; Gray, Harry B.; Carim, Azhar; Lewis, Nathan Saul

Option: Chemistry

Abstract

Emergent phenomena are the result of ignorant, non-directed individual actors that work in ensemble and produce complex patterns or behaviors. Due to a set of generally applied rules, the individual actors operate ignorant of the overall order, instead aware of only close-by neighbors, causing long-range order to develop through a bottom-up method. Such behaviors as the flocking of birds, branching of corals, and bending of palm trees are all influenced by emergent phenomena. As technology advances, there is increased need for smaller and more complex structures to push the limits of computation, optics, catalysis, and a host of other applications. Many of the challenges in these fields have been answered with top-down directed approaches, such as lithography, that are expensive both in terms of energy in time for developing small, ordered structures. A number of bottom-up approaches to creating micro and nanoscale order have arisen in recent decades, such as drying self-assembly, self-assembling supramolecular structures, DNA nanotechnology, and LIPSS, with the hopes of replacing costly top-down approaches. This thesis will discuss the development of the recently described emergent growth phenomenon, termed inorganic phototropic growth (IPG), applied to Cu₂O. IPG proceeds via the illuminated electrodeposition of semiconductors, wherein anisotropic light scattering leads to structure formation. IPG of Cu₂O is unique to previous reports in that morphology development is sensitive to a variety of chemical parameters, suggesting possible increased structure tuneability.