Surface instabilities and interfacial phenomena for nanomanufacturing at the atomically-thin limit

Two-dimensional (2D) layered materials, exemplified by the prototypical graphene, have been intensively studied for their diverse material properties and superlative mechanical strength. Due to their atomically-thin nature, weak basal plane van der Waals interactions, and vanishing bending stiffness, 2D materials are extremely flexible and thus susceptible to mechanical instabilities that result in deformed out-of-plane morphologies. Such unique combination of material properties and mechanical anisotropy presents new scientific and practical challenges, but also enables novel opportunities in the nanomanufacture of 2D materials and of their derivative materials systems and devices. Surface instabilities (e.g. wrinkling and buckling) and interfacial phenomena (e.g. delamination) are typically deemed as engineering nuisances and failure modes. However, these universally ubiquitous phenomena can instead be harnessed to realize novel strategies and architectures for precise manipulation and assembly of 2D and other low-dimensional nanoscale materials, the combination of which contributes to an ever-growing toolset of capabilities towards layer-by-layer nanomanufacturing at the atomically-thin limit. This dissertation details new methods that have been developed to deterministically create hierarchical and deformed 2D materials via large-scale elastic strain engineering and controlled shape memory deformation. The emergent tunable 3D architectures arising from flat 2D materials exhibit large-scale, uniform, and well-organized patterns with characteristic length scales spanning from tens of nanometers to few microns without any a priori patterning or lithographic definition of the constituent sub-nanometer 2D thin films. By controlling bulk substrate deformation, this highly robust and scalable process imparts spatially heterogeneous strain gradients that perturb the intrinsic lattice structure and consequently the local optoelectronic properties of atomically-thin monolayer graphene analogs such as semiconducting transition metal chalcogenides, thus creating highly uniform and periodic lateral superlattice configurations. In addition, the generality of this self-patterning scheme allows for facile and scalable definition of nanoscale architectures for template guided nano-convective/capillary self-assembly of arbitrary 0D/1D nanoparticles onto deformed 2D substrates. Here, high quality colloidally prepared gold nanoparticles of diverse shapes and sizes readily self-assemble into various tunable structured mixed-dimensional metamaterials, opening the opportunity to investigate emergent phenomena such as those arising from coupling between metallic plasmonic nanostructures/nanoparticles with excitons and other quasiparticles in 2D materials. Finally, with the eventual goal towards large-scale nano-manufacturing of these 2D materials and devices, a new technique has been developed to cleanly and sustainably manufacture graphene and recycle the catalyst metal substrate using benign materials. By separating the 2D material from the growth substrate via electrochemical interfacial delamination, this method forgoes the harsh chemicals typically used in conventional processing of 2D materials while simultaneously avoiding expenditure of the expensive precursors, thus leading to scalable production of high quality, clean graphene with reduced negative externalities.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2018

Author dc:creator

• Wang, Cai Mike

Contributors dc:contributor

• Nam, SungWoo
• Saif, Taher
• Murphy, Catherine J.
• Lyding, Joseph W.
• Mensing, Glennys A

• conformable materials
• 0D/1D materials
• 2D materials
• 2.5D
• 3D
• adaptive materials
• atomic force microscopy
• atomically thin
• AuNPs
• buckling
• carbon dioxide
• chemical vapour deposition
• CO2
• copper
• crumpling
• deformation
• delamination
• dichroism
• electrochemistry
• electrolyte
• excitonics
• field-effect transistor
• flexible electronics
• gold nanoparticles
• graphene
• grating
• green chemistry
• green manufacturing
• heterostructures
• interfaces
• layered materials
• lithography-free
• low-dimensional materials
• materials processing
• mechanical instabilities
• metamaterials
• molybdenum disulphide
• MoS2
• nano-manufacturing
• nanomaterials
• nanoparticles
• nanoscale patterning
• nano-templating
• photoluminescence
• plasmonics
• Raman spectroscopy
• self-assembly
• semiconductors
• strain
• surface instabilities
• surface wrinkling
• sustainable manufacturing
• three-dimensional
• transition metal chalcogenide
• two-dimensional materials
• van der Waals materials

Statement dc:rights

• Copyright 2018 Michael Cai Wang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/101761

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/101761