Chao, Zhongmou
(2021)
Silver Filament Formation/Dissolution Dynamics Through a Polymer/Ionic liquid Composite by Direct-write.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
A direct-write, electrochemical approach to the formation and dissolution of silver nanofilaments is demonstrated through a novel polymer electrolyte consisting of a UV-crosslinkable polymer, polyethylene glycol diacrylate (PEGDA) and an ionic liquid (IL), 1-butyl-3-methylimadozolium hexafluorophosphate ([BMIM]PF6). Nanofilaments are formed and dissolved at pre-programmed locations with a conductive atomic force microscope (c-AFM) using a custom script. Although the formation time generally decreases with increasing bias from 0.7 to 3.0 V, an unexpected non-monotonic maximum is observed ~2.0 V. At voltages approaching this region of inverted kinetics, IL electric double layers (EDLs) become detectable; thus, the increased nanofilament formation time can be attributed to electric field screening, which hinders silver electromigration and deposition. Scanning electron microscopy confirms that nanofilaments formed in this inverted region have significantly more lateral and diffuse features. Time dependent formation currents reveal two types of nanofilament growth dynamics: abrupt, where the resistance decreases sharply over as little as a few ms, and gradual where it decreases more slowly over hundreds of ms. Whether the resistance change is abrupt or gradual depends on the extent to which the EDL screens the electric field. Silver nanofilaments with gradual growth dynamics have potential application in neuromorphic computing. In this study, a linear (R2 > 0.9) dependence of conductance on the number of bias pulses is demonstrated—a signature feature that is required for neuromorphic application. Hundreds of distinguishable conductance states ranging from 235 to 260 microsimens can be accessed using a low read bias. These results show that novel PEGDA/IL composite electrolyte enables the gradual formation and dissolution of silver nanofilament with tunable conductance states, making it a promising candidate to advance neuromorphic applications.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
26 January 2021 |
| Date Type: |
Publication |
| Defense Date: |
28 October 2020 |
| Approval Date: |
26 January 2021 |
| Submission Date: |
30 October 2020 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
189 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
silver filament, polymer electrolyte, ionic liquid, neuromorphic computing |
| Date Deposited: |
26 Jan 2021 18:12 |
| Last Modified: |
26 Jan 2021 18:12 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/39827 |
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