Date of Award

2022

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering (PhD)

Administrative Home Department

Department of Electrical and Computer Engineering

Advisor 1

Paul L. Bergstrom

Committee Member 1

Durdu Guney

Committee Member 2

Andrew J. Gross

Committee Member 3

Smitha Rao Hatti

Abstract

Conductive polymers have recently attracted a lot of attention in advanced technologies because of their unique characteristics. Among the conductive polymers, polyaniline (PANi) has been studied widely because of its environmental stability, simple processing, inexpensive source monomer, and, most importantly, its controllable wide conductivity range due to the doping (protonation) process. These characteristics of PANi make it a strong candidate for applications in numerous areas such as biosensors, transparent display, photovoltaic devices, batteries, and, more recently, flexible electronics. Even with the many studies that have been conducted in this field, however, future advances are still needed to optimize the processability, conductivity, and environmental stability of PANi through modification of polymerization conditions, deposition techniques, and doping processes for specific applications. This dissertation focuses on optimizing PANi thin film deposition using the Langmuir-Blodget Trough (LB-Trough) technique. In this regard, the impact of the solvent composition for the mixture preparation, the PANi polymer chain molecular weight (5000, 50000, and 100000 g.mol-1), and the subphase chemistry have been investigated to explore the impact on the physical properties of the PANi film characteristics and processing. In addition, the electrical characteristics of the LB-Trough deposited PANi film using interdigitated electrodes by employing two methods of doping and electrical conductivity aging were studied. The results revealed the most promising thin-film quality with regard to film uniformity within a sample and from sample to sample and the reproducible nanometer-scale deposition across many samples when using the lowest molecular weight available, 5000 g.mol-1, and employing NMP+chloroform as the solvent. The film thickness measurement revealed a range between 1.1 and 2.2 nm per single-layer film thickness deposition. The highest conductivity measured was 41 S.m-1 for a 45 LB-Trough deposited PANi film using 1.5 M HCl as the doping source and a 24 h exposure time. Thirty days of electrical conductivity aging data in the lab environment determined a steep degradation in conductivity during the first five days after deposition before the sample reached its steady state. The redox reversibility testing demonstrated that 72% of the initial conductivity may be recovered after ten aging and recovery cycles.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Saturday, April 15, 2023

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