Reproducibility of electrostatically self-assembled electro-optic thin films

Abstract

Thin film electro-optic materials have been synthesized by a novel electrostatic self-assembly (ESA) method using both manual and automated processes. This paper discusses the reproducibility of such ESA-formed electro-optic thin films formed by both methods. Multiple films were fabricated based on the same layer-by-layer molecular design. They were evaluated using UV-vis spectroscopy and multiwavelength ellipsometry to demonstrate linear growth with the addition of layers, and to measure the thickness of the formed film. Their electro-optic coefficients have also been measured using Mach-Zehnder and Teng and Man approaches. Variations in the properties, including absorption, thickness and electro-optic coefficients, for all of the test samples are reported. We analyze possible causes for such variations, which include time-dependent differences in solution chemistry and differences between manual and automated fabrication processes. We further suggest approaches to both the solution chemistry and thin film design that may be used to limit the effect of such variations on the performance of electro-optic devices.