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Date Permissions Signed
Date of Award
Department or Program Affiliation
Master of Science (MS)
Patrick, David L.
Johnson, Brad L., 1961-
The advancement of semiconducting materials is paramount to the future of electronics. Organic semiconducting materials are of particular interest due to their significantly lower processing cost compared to traditional inorganic semiconducting materials, such as silicon. However, the present toolkit for solution-based controlled growth of polycrystalline thin films is lacking. Therefore, the purpose of this research is to build such a toolkit, wherein tunable parameter relationships of organic thin-film growth are evaluated and compared both experimentally and computationally. A multi-scale model has been developed, which combines mean field rate equations with a self-consistent treatment of the critical stable monomer cluster size, and a stochastic treatment of nucleation once beyond the critical monomer concentration. The result of the simulation is a 2D monomer concentration landscape and a map of crystal locations; the evolution of each component can be viewed over the time span of the experiment. Using bright-field fluorescence video-microscopy, the same information is obtained experimentally. Computational and experimental spacing statistics, radial monomer concentrations, and parameter relationships are explored using these methods. Understanding these factors will further our ability to understand fundamental parameter relationships of OVLS (organic-vapor-liquid-solid) deposition, polycrystalline thin-film nucleation and the ability to predict optimal parameters for thin-film architectural growth patterns; one such example being shape engineering crystals to grow in holey patterns for novel applications, such as photonics. Furthermore, a phototransistor, fabricated using the OVLS deposition scheme, is characterized and compared to a recently-published and structurally-similar device.
organic crystal nucleation, monomer concentration landscape, multi-scale model, burst nucleation, nucleation in solvent, controlled crystal growth, phototransistor
Western Washington University
Subject – LCSH
Nucleation; Organic semiconductors; Polycrystals; Multiscale modeling
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Doran, Haley, "Organic Crystal Nucleation in Ultrathin Liquid Films: Applications of Computational and Experimental Methods for the Exploration of Dynamic Spatial Relationships and Controlled Growth" (2021). WWU Graduate School Collection. 1009.