Template-Free Assembly of Three Dimensional Mesostructures via Polarization Control

Author: Reich, Natasha D.

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Lewis, Nathan Saul

Committee Members: Gray, Harry B.; Okumura, Mitchio; Blake, Geoffrey A.; Carim, Azhar I.; Lewis, Nathan Saul

Option: Chemistry

Abstract

Plants are inherently sessile and thus exhibit adaptive morphologies to forage for essential resources such as light. For example, palm trees grow with a pronounced tilt towards the time-averaged solar position to optimize light collection. In analogy, electrochemical growth of semiconductor material under illumination can result in spontaneous self-organization. Such inorganic phototropic growth can produce mesostructured deposits consisting of ordered nanoscale features over cm2 areas, despite a lack of lithographic processing, structured light fields, or templating agents (ligands, surfactants, etc.). Precise deposit morphologies are determined by the characteristics of the input illumination. Growth using linearly polarized illumination produces highly anisotropic lamellar arrays with a feature pitch proportional to the wavelength. Abrupt, orthogonal shifts in the polarization direction during growth reorient the direction of the in-plane anisotropy producing woodpile architectures with independently tunable layer heights. Moreover, spatial registration between alternating layers is produced via optical coupling across the intermediary layer. The investigations described herein demonstrate that inorganic phototropic growth enables programmable, high-throughput fabrication of complex three-dimensional lattices that cannot be achieved easily, if at all, via conventional means.