High-k dielectric layers and their application in organic electronics
- Solution processed organic field effect transistor (OFETs) have being proposed for low-cost electronic applications such as sensors, RFID tags, and electronic paper. In order to achieve high performance, the effects of microstructure on charge transport as well as the design of new organic semiconductors have been investigated. Equally important, however, is the influence of the gate dielectric interface on the properties of organic semiconductors for various applications. In the first chapter, the functionality of a dual gate transistor as a chemical sensor will be demonstrated. The top high-[kappa] dielectric, Al2O3, is deposited on a conventional single gate OTFT to build the sensing element. When polar molecules of interest attach to the top high-k dielectric, an electric field is induced on the top surface of semiconductor, affecting the response of the transistor thereby providing a sensing mechanism. As a result, such top dielectric sensing architecture produces a high-sensitivity response and mitigates the poor ambient stability of organic semiconductors. The second chapter of this dissertation will focus on room-temperature, solution-based fabrication of high-[kappa] ZrO2 thin films for low-voltage-operated OFETs. An alternative UV curing method for the densification of Zr-based gel films, which allows for low-temperature processing, is compared to the conventional thermal annealing method. Electrical and microstructural analysis shows that UV-curing induces the decomposition of organic-metal bonds and causes the densification of the metal oxide film, just as the conventional thermal annealing of gel films does, resulting in a high-[kappa] dielectric layer from Zr-based solutions. Using this dielectric layer with an octadecylphosphonic acid self-assembled monolayer, solution-processed polymer OFETs with PBTTT-C-14 as the organic semiconductor function well at low voltage (below -3 V). The effect of SAM on the morphology and microstructure of the organic semiconductor deposited on the ZrO2 dielectrics is investigated. We also demonstrate a solution-processed OFETs fabricated on a flexible substrate at low temperature (T< 70°C). In third chapter, the third part of the presentation will focus on dielectric surface modification effects on an ambipolar organic semiconductor in order to control on-set voltage by introducing known amounts of deep trap states. Self-assembled monolayers with different head group were used to modify the charge transport properties of an ambipolar organic semiconductor, poly(3,6-bis-selenophene-2-octyl-1-dodecyl-diketopyrrolopyrrole- co-benzothiadiazole (PSeDPPBT). To further investigate the origin of the surface modification effect, micro- and electronic structure of PSeDPPBT were characterized with grazing incident x-ray diffraction and temperature dependent charge transport measurements.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Park, Young Min
|Stanford University, Department of Materials Science and Engineering
|McIntyre, Paul Cameron
|McIntyre, Paul Cameron
|Statement of responsibility
|Young Min Park.
|Submitted to the Department of Materials Science and Engineering.
|Thesis (Ph.D.)--Stanford University, 2012.
- © 2012 by Young Min Park
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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