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High-Performance Organic Transistors Through Rational Device Design

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High-Performance Organic Transistors Through Rational Device Design
Waldrip, Matthew
Organic semiconductors have sparked significant attention investment as flexible, solutionprocessable, and chemically tunable electronic materials. Improvements in charge carrier mobility put organic semiconductors in a competitive position for incorporation in a variety of (opto-)electronic applications. The organic field-effect transistor (OFET) is one of the most important devices based on organic semiconductors, as it is the fundamental building block of many applications. The work outlined in this thesis encompasses rational device design wherein advancements in the performance of OFETs are made through careful engineering of all the constituent components of the transistor. We begin by outlining the fundamental physics governing charge injection in organic semiconductors and define the origins and consequences of contact resistance from charge carrier injection. Methods for measuring and characterizing contact resistance are discussed and are accompanied by the most successful approaches for reducing contact resistance, highlighting the fast and significant progress that has been witnessed in the last 5-7 years. We investigate a novel method of treating the contacts, namely flash annealing, and examine the results through the lens of both contact resistance and electronic traps. Studies are then enhanced through large-scale computer simulations where thousands of unique transistors are screened for properties that allow for the relaxation of parameters deemed critical to device operation. A fabrication window where the charge carrier mobility of the OFET is insensitive to the contact resistance is discovered, and the knowledge is applied to design and fabricate an all-organic, fully-printed, flexible OFET with mobility exceeding 5 cm2/Vs, a record for this type of transistor. The simulations are then revisited to uncover a method by which the standards of semiconductor purity can be relaxed, and we demonstrate the device’s tolerance to electronic traps by purposefully adding a 2% concentration of impurities into the semiconductor while maintaining the same OFET mobility. Together the results included in this thesis represent significant advancements in organic field-effect transistor design and operation, providing new understanding, methodology, and realizations of technology in the face of real-world imperfections.
Device Simulation
Flexible Electronics
Organic Field-Effect Transistor
Organic Semiconductor
Thin-Film Transistor
Jurchescu, Oana D (advisor)
Ghadiri, Elham (committee member)
Srimath Kandada, Ajay Ram (committee member)
Thonhauser, Timo (committee member)
Winter, Stephen M (committee member)
2023-01-24T09:35:42Z (accessioned)
2022 (issued)
Physics (discipline)
2027-12-31 (terms)
2027-12-31 (liftdate)
http://hdl.handle.net/10339/101771 (uri)
en (iso)
Wake Forest University

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