Ion penetration in conjugated polymers : connecting structural effects and electronic transport
Abstract/Contents
- Abstract
- Ionic liquids are increasingly employed as dielectrics to generate high charge densities and enable low-voltage operation with organic semiconductors. However, effects on structure and morphology of the active material are not fully known, particularly for permeable semiconductors such as conjugated polymers, in which ions from the ionic liquid can enter and electrochemically dope the semicrystalline film. To understand when ions enter, where they go, and how they affect the film, thin films of the archetypal semiconducting polymer, poly(3-hexylthiophene) (P3HT), are electrochemically doped with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), the archetypal ionic liquid. High-resolution, ex situ x-ray diffraction measurements and complete pole figures reveal changes with applied voltage, cycling, and frequency in lattice spacing, crystallite orientation, and crystallinity in the bulk and at the buried interface. Dopant ions penetrate the film and enter the crystallites at sufficiently high voltages and low frequencies. Upon infiltrating crystallites, ions permanently expand lamellar stacking and contract pi-stacking. Cycling amplifies these effects, but higher frequencies mitigate the expansion of bulk crystallites as ions are hindered from entering crystallites. Important metrics for electronic transport such as mobility and drain current ON/OFF ratio are also affected following patterns analogous to those seen for lattice spacing and crystallinity under two operating regimes. This mechanistic understanding of the structural effects of ion penetration will help develop models of the frequency and voltage impedance response of electrochemically doped conjugated polymers and advanced electronic applications.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Guardado, Jesus Omar |
|---|---|
| Degree supervisor | Salleo, Alberto |
| Thesis advisor | Salleo, Alberto |
| Thesis advisor | Appel, Eric (Eric Andrew) |
| Thesis advisor | Brongersma, Mark L |
| Degree committee member | Appel, Eric (Eric Andrew) |
| Degree committee member | Brongersma, Mark L |
| Associated with | Stanford University, Department of Materials Science and Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Jesus Omar Guardado. |
|---|---|
| Note | Submitted to the Department of Materials Science & Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Jesus Omar Guardado
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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