Online Ph.D. Defense: “Microstructure Control in Organic and Hybrid Semiconductors and its Impact on Device Performance”
Mr. Andrew Zeidell, Ph.D. Candidate
Mentor: Professor Oana Jurchescu
Department of Physics
Wake Forest University
Tuesday, April 21, 2020 at 2:00 – 3:00 PM
(Private defense will follow public presentation.)
Video conference link: https://wakeforest-university.zoom.us/j/334962509
ABSTRACT
Since the identification of anthracene as a semiconducting material in the 1960s, the field of organic electronics has seen a remarkable growth, with several breakthroughs that have changed our lives. Subsequent developments in chemical design have resulted in small molecule organic semiconductors with functionalized backbones, creating a new paradigm for organic electronics: solution processability. Solution processability increases the viability of novel and scalable deposition techniques, such as inkjet printing and spray deposition, but can often result in much more variable device performance due to the disordered microstructure in thin films deposited this way. Factors impacting the overall device performance are manifold and often interdependent: device design, solid-state packing, microstructure, and molecular structure all impact the electrical properties in intricate ways. The overarching goal of my PhD research was improving thin-film microstructure as a route to improve performance in both hybrid organic-inorganic and organic field-effect transistors (FETs). The FET is an excellent experimental tool to study charge carrier mobility in materials, as they enable the extraction of charge carrier mobilities from current-voltage characteristics of the device, with no approximations or assumptions being necessary. This research has specifically focused on using processing and post-processing techniques to control the degree of order in thin films, and characterizing the resulting structures using techniques such as X-ray diffraction, microscopy, and electrical measurements. This work encompasses quantitative studies on the use of solvent vapor annealing to improve thin-film morphology, and spans device design, fabrication, and characterization, as well as novel applications of OFETs in medical devices and large area sensors.
