{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/108221"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/108221","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Mechanical self-assembly of deformed 2D materials for advanced functionalities","abstract":"Introducing three-dimensionality to two-dimensional (2D) materials opened new possibilities and novel applications in material system design. Extraordinary intrinsic properties of 2D materials have attracted scientific research communities, and various 2D material – based structures and devices have been proposed and demonstrated. Given the fascinating electrical, optical, and thermal properties of 2D materials, constructing three-dimensional (3D) structures out of 2D materials would make 2D systems even more interesting by providing means of extrinsic modulation of material properties of 2D materials. 2D materials frequently undergo out-of-plane deformation because the atomic thinness of 2D materials leads to rippling, wrinkling, and folding at the surface during synthesis and transfer processes. Those out-of-plane deformations are neither organized nor controllable structures, and therefore, they have often been considered inevitable defects. However, recent studies have reported tunable electrical, chemical, optical, and mechanical properties when a controlled in-plane strain gradient is applied to 2D lattice structures. This implies that such out-of-plane deformations with structural control can be useful tools for material engineering. Therefore, we seek ways to manipulate the deformation of 2D materials to modulate material properties for advanced functionalities. One of our strategies to architecture 2D materials is inspired by fine wrinkle formation that occurs when there is a strain mismatch between a thin film and an underlying substrate. We use extreme-case strain mismatch, often up to 300 percent or more. In addition, we control the direction of prestrains to create uniaxially or biaxially crumpled 2D materials with a uniaxial prestrain or biaxial prestrains, respectively. The resulting structure is a mechanically self-assembled, buckle-delaminated structure with delocalized crumples and inhomogeneous strain in the crumpled 2D lattice. Furthermore, we create mixed-dimensional structures by combining our architecturing strategy with unconventional crack lithography. Through the crack lithography – inspired strategy, heterogeneous 2D-3D mixed-dimensional structures are formed with localized crumples. These strategies are universally applicable to 2D materials and 2D material – based hybrid structures, such as graphene, molybdenum disulfide (MoS2), and graphene – gold nanoparticles (Au NPs) hybrid structures. We further explore advanced functionalities of buckle-delaminated crumpled structures of 2D materials and 2D materials – based hybrid structures. The crumpled graphene – Au NPs hybrid structure demonstrates advanced functionality based on the topography of deformed 2D materials. In the hybrid structure, Au NPs are formed on a graphene surface, through thermal dewetting of gold thin film. The graphene is then deformed into a 3D crumpled structure. The crumpled structure effectively enhances localized electromagnetic fields between adjacent Au NPs by reducing the gap between Au NPs and helps utilize the 3D focal volume of the incident laser. Therefore, the crumpled hybrid structure – based surface-enhanced Raman spectroscopy (SERS) sensor exhibits an order of magnitude higher sensitivity, compared to a flat hybrid structure – based SERS sensor. Additionally, the crumpled hybrid structure – based SERS sensor can be easily applied on an arbitrary curvilinear surface demonstrating its potential for in situ SERS assays. We further applied the crumpled hybrid structure of graphene – Au NPs to create a photodetector with plasmonically enhanced photoresponsivity and high stretchability. Gold nanoparticles in the hybrid structure effectively enhance photoresponsivity, and further enhancement is achieved by material densification by crumpling the hybrid structure. As a result, we demonstrate 1200% enhanced photoresponsivity over a flat graphene device by combining the plasmonic effect and material densification. The crumpled structure also provides an exceptional 200% stretchability. The fabricated structure is mechanically robust, with no failure observed after 1000 cycles of stretching and releasing. The deformed 2D material system also provides a material platform for strain engineering of 2D materials. We created a 3D crumpled structure with a semiconducting 2D material, MoS2, to create inhomogeneous strain in the MoS2 lattice. This continuous strain change across the deformed structure induces a bandgap energy gradient, and therefore, provides efficient transport paths for photoexcited excitons in the deformed 2D lattice. We further demonstrated dynamic photoresponsivity modulation by structural modulation of a deformed 2D material, implying exciton drift modulation in a crumpled and flattened lattice structure. In conclusion, we have demonstrated effective strategies to create deformed 2D material systems with various levels of structural complexity, and related applications utilizing the unique topography and the strain gradient simultaneously created in the deformed lattice. We believe our approach to deforming 2D materials and achieving advanced functionalities contribute to the related research communities by demonstrating a way to extrinsically manipulate 2D materials' topography, and therefore modulate intrinsic properties.","abstract_html":"Introducing three-dimensionality to two-dimensional (2D) materials opened new possibilities and novel applications in material system design. Extraordinary intrinsic properties of 2D materials have attracted scientific research communities, and various 2D material – based structures and devices have been proposed and demonstrated. Given the fascinating electrical, optical, and thermal properties of 2D materials, constructing three-dimensional (3D) structures out of 2D materials would make 2D systems even more interesting by providing means of extrinsic modulation of material properties of 2D materials. 2D materials frequently undergo out-of-plane deformation because the atomic thinness of 2D materials leads to rippling, wrinkling, and folding at the surface during synthesis and transfer processes. Those out-of-plane deformations are neither organized nor controllable structures, and therefore, they have often been considered inevitable defects. However, recent studies have reported tunable electrical, chemical, optical, and mechanical properties when a controlled in-plane strain gradient is applied to 2D lattice structures. This implies that such out-of-plane deformations with structural control can be useful tools for material engineering. Therefore, we seek ways to manipulate the deformation of 2D materials to modulate material properties for advanced functionalities. One of our strategies to architecture 2D materials is inspired by fine wrinkle formation that occurs when there is a strain mismatch between a thin film and an underlying substrate. We use extreme-case strain mismatch, often up to 300 percent or more. In addition, we control the direction of prestrains to create uniaxially or biaxially crumpled 2D materials with a uniaxial prestrain or biaxial prestrains, respectively. The resulting structure is a mechanically self-assembled, buckle-delaminated structure with delocalized crumples and inhomogeneous strain in the crumpled 2D lattice. Furthermore, we create mixed-dimensional structures by combining our architecturing strategy with unconventional crack lithography. Through the crack lithography – inspired strategy, heterogeneous 2D-3D mixed-dimensional structures are formed with localized crumples. These strategies are universally applicable to 2D materials and 2D material – based hybrid structures, such as graphene, molybdenum disulfide (MoS2), and graphene – gold nanoparticles (Au NPs) hybrid structures. We further explore advanced functionalities of buckle-delaminated crumpled structures of 2D materials and 2D materials – based hybrid structures. The crumpled graphene – Au NPs hybrid structure demonstrates advanced functionality based on the topography of deformed 2D materials. In the hybrid structure, Au NPs are formed on a graphene surface, through thermal dewetting of gold thin film. The graphene is then deformed into a 3D crumpled structure. The crumpled structure effectively enhances localized electromagnetic fields between adjacent Au NPs by reducing the gap between Au NPs and helps utilize the 3D focal volume of the incident laser. Therefore, the crumpled hybrid structure – based surface-enhanced Raman spectroscopy (SERS) sensor exhibits an order of magnitude higher sensitivity, compared to a flat hybrid structure – based SERS sensor. Additionally, the crumpled hybrid structure – based SERS sensor can be easily applied on an arbitrary curvilinear surface demonstrating its potential for in situ SERS assays. We further applied the crumpled hybrid structure of graphene – Au NPs to create a photodetector with plasmonically enhanced photoresponsivity and high stretchability. Gold nanoparticles in the hybrid structure effectively enhance photoresponsivity, and further enhancement is achieved by material densification by crumpling the hybrid structure. As a result, we demonstrate 1200% enhanced photoresponsivity over a flat graphene device by combining the plasmonic effect and material densification. The crumpled structure also provides an exceptional 200% stretchability. The fabricated structure is mechanically robust, with no failure observed after 1000 cycles of stretching and releasing. The deformed 2D material system also provides a material platform for strain engineering of 2D materials. We created a 3D crumpled structure with a semiconducting 2D material, MoS2, to create inhomogeneous strain in the MoS2 lattice. This continuous strain change across the deformed structure induces a bandgap energy gradient, and therefore, provides efficient transport paths for photoexcited excitons in the deformed 2D lattice. We further demonstrated dynamic photoresponsivity modulation by structural modulation of a deformed 2D material, implying exciton drift modulation in a crumpled and flattened lattice structure. In conclusion, we have demonstrated effective strategies to create deformed 2D material systems with various levels of structural complexity, and related applications utilizing the unique topography and the strain gradient simultaneously created in the deformed lattice. We believe our approach to deforming 2D materials and achieving advanced functionalities contribute to the related research communities by demonstrating a way to extrinsically manipulate 2D materials' topography, and therefore modulate intrinsic properties.","abstract_has_math":false,"creators":["Leem, Juyoung"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Nam, SungWoo","Murphy, Catherine J","Mason, Nadya","Cai, Lili"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-08-27T00:46:48Z","date_published":"2020-08-27T00:46:48Z","updated_at":"2026-07-22T22:24:48Z","subjects":["2D Materials","Deformation","Mechanical self-assembly","Optoelectronics","Plasmonics"],"languages":["en"],"rights":["Copyright 2020 Juyoung Leem"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/108221","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Nam, SungWoo","Murphy, Catherine J","Mason, Nadya","Cai, Lili"]},{"key":"dc:creator","label":"Author","values":["Leem, Juyoung"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-08-27T00:46:48Z","2022-08-27T00:51:40Z","2020-02-11","2020-05"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["2D Materials","Deformation","Mechanical self-assembly","Optoelectronics","Plasmonics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Juyoung Leem"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/108221"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Introducing three-dimensionality to two-dimensional (2D) materials opened new possibilities and novel applications in material system design. Extraordinary intrinsic properties of 2D materials have attracted scientific research communities, and various 2D material – based structures and devices have been proposed and demonstrated. Given the fascinating electrical, optical, and thermal properties of 2D materials, constructing three-dimensional (3D) structures out of 2D materials would make 2D systems even more interesting by providing means of extrinsic modulation of material properties of 2D materials. 2D materials frequently undergo out-of-plane deformation because the atomic thinness of 2D materials leads to rippling, wrinkling, and folding at the surface during synthesis and transfer processes. Those out-of-plane deformations are neither organized nor controllable structures, and therefore, they have often been considered inevitable defects. However, recent studies have reported tunable electrical, chemical, optical, and mechanical properties when a controlled in-plane strain gradient is applied to 2D lattice structures. This implies that such out-of-plane deformations with structural control can be useful tools for material engineering. Therefore, we seek ways to manipulate the deformation of 2D materials to modulate material properties for advanced functionalities. One of our strategies to architecture 2D materials is inspired by fine wrinkle formation that occurs when there is a strain mismatch between a thin film and an underlying substrate. We use extreme-case strain mismatch, often up to 300 percent or more. In addition, we control the direction of prestrains to create uniaxially or biaxially crumpled 2D materials with a uniaxial prestrain or biaxial prestrains, respectively. The resulting structure is a mechanically self-assembled, buckle-delaminated structure with delocalized crumples and inhomogeneous strain in the crumpled 2D lattice. Furthermore, we create mixed-dimensional structures by combining our architecturing strategy with unconventional crack lithography. Through the crack lithography – inspired strategy, heterogeneous 2D-3D mixed-dimensional structures are formed with localized crumples. These strategies are universally applicable to 2D materials and 2D material – based hybrid structures, such as graphene, molybdenum disulfide (MoS2), and graphene – gold nanoparticles (Au NPs) hybrid structures. We further explore advanced functionalities of buckle-delaminated crumpled structures of 2D materials and 2D materials – based hybrid structures. The crumpled graphene – Au NPs hybrid structure demonstrates advanced functionality based on the topography of deformed 2D materials. In the hybrid structure, Au NPs are formed on a graphene surface, through thermal dewetting of gold thin film. The graphene is then deformed into a 3D crumpled structure. The crumpled structure effectively enhances localized electromagnetic fields between adjacent Au NPs by reducing the gap between Au NPs and helps utilize the 3D focal volume of the incident laser. Therefore, the crumpled hybrid structure – based surface-enhanced Raman spectroscopy (SERS) sensor exhibits an order of magnitude higher sensitivity, compared to a flat hybrid structure – based SERS sensor. Additionally, the crumpled hybrid structure – based SERS sensor can be easily applied on an arbitrary curvilinear surface demonstrating its potential for in situ SERS assays. We further applied the crumpled hybrid structure of graphene – Au NPs to create a photodetector with plasmonically enhanced photoresponsivity and high stretchability. Gold nanoparticles in the hybrid structure effectively enhance photoresponsivity, and further enhancement is achieved by material densification by crumpling the hybrid structure. As a result, we demonstrate 1200% enhanced photoresponsivity over a flat graphene device by combining the plasmonic effect and material densification. The crumpled structure also provides an exceptional 200% stretchability. The fabricated structure is mechanically robust, with no failure observed after 1000 cycles of stretching and releasing. The deformed 2D material system also provides a material platform for strain engineering of 2D materials. We created a 3D crumpled structure with a semiconducting 2D material, MoS2, to create inhomogeneous strain in the MoS2 lattice. This continuous strain change across the deformed structure induces a bandgap energy gradient, and therefore, provides efficient transport paths for photoexcited excitons in the deformed 2D lattice. We further demonstrated dynamic photoresponsivity modulation by structural modulation of a deformed 2D material, implying exciton drift modulation in a crumpled and flattened lattice structure. In conclusion, we have demonstrated effective strategies to create deformed 2D material systems with various levels of structural complexity, and related applications utilizing the unique topography and the strain gradient simultaneously created in the deformed lattice. We believe our approach to deforming 2D materials and achieving advanced functionalities contribute to the related research communities by demonstrating a way to extrinsically manipulate 2D materials' topography, and therefore modulate intrinsic properties.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-05-01","The student, Juyoung Leem, accepted the attached license on 2020-02-10 at 17:54.","The student, Juyoung Leem, submitted this Dissertation for approval on 2020-02-10 at 18:16.","This Dissertation was approved for publication on 2020-02-11 at 15:52.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14867 on 2020-08-25 at 17:38:33","Made available in DSpace on 2020-08-27T00:46:48Z (GMT). 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Extraordinary intrinsic properties of 2D materials have attracted scientific research communities, and various 2D material – based structures and devices have been proposed and demonstrated. Given the fascinating electrical, optical, and thermal properties of 2D materials, constructing three-dimensional (3D) structures out of 2D materials would make 2D systems even more interesting by providing means of extrinsic modulation of material properties of 2D materials. 2D materials frequently undergo out-of-plane deformation because the atomic thinness of 2D materials leads to rippling, wrinkling, and folding at the surface during synthesis and transfer processes. Those out-of-plane deformations are neither organized nor controllable structures, and therefore, they have often been considered inevitable defects. However, recent studies have reported tunable electrical, chemical, optical, and mechanical properties when a controlled in-plane strain gradient is applied to 2D lattice structures. This implies that such out-of-plane deformations with structural control can be useful tools for material engineering. Therefore, we seek ways to manipulate the deformation of 2D materials to modulate material properties for advanced functionalities. One of our strategies to architecture 2D materials is inspired by fine wrinkle formation that occurs when there is a strain mismatch between a thin film and an underlying substrate. We use extreme-case strain mismatch, often up to 300 percent or more. In addition, we control the direction of prestrains to create uniaxially or biaxially crumpled 2D materials with a uniaxial prestrain or biaxial prestrains, respectively. The resulting structure is a mechanically self-assembled, buckle-delaminated structure with delocalized crumples and inhomogeneous strain in the crumpled 2D lattice. Furthermore, we create mixed-dimensional structures by combining our architecturing strategy with unconventional crack lithography. Through the crack lithography – inspired strategy, heterogeneous 2D-3D mixed-dimensional structures are formed with localized crumples. These strategies are universally applicable to 2D materials and 2D material – based hybrid structures, such as graphene, molybdenum disulfide (MoS2), and graphene – gold nanoparticles (Au NPs) hybrid structures. We further explore advanced functionalities of buckle-delaminated crumpled structures of 2D materials and 2D materials – based hybrid structures. The crumpled graphene – Au NPs hybrid structure demonstrates advanced functionality based on the topography of deformed 2D materials. In the hybrid structure, Au NPs are formed on a graphene surface, through thermal dewetting of gold thin film. The graphene is then deformed into a 3D crumpled structure. The crumpled structure effectively enhances localized electromagnetic fields between adjacent Au NPs by reducing the gap between Au NPs and helps utilize the 3D focal volume of the incident laser. Therefore, the crumpled hybrid structure – based surface-enhanced Raman spectroscopy (SERS) sensor exhibits an order of magnitude higher sensitivity, compared to a flat hybrid structure – based SERS sensor. Additionally, the crumpled hybrid structure – based SERS sensor can be easily applied on an arbitrary curvilinear surface demonstrating its potential for in situ SERS assays. We further applied the crumpled hybrid structure of graphene – Au NPs to create a photodetector with plasmonically enhanced photoresponsivity and high stretchability. Gold nanoparticles in the hybrid structure effectively enhance photoresponsivity, and further enhancement is achieved by material densification by crumpling the hybrid structure. As a result, we demonstrate 1200% enhanced photoresponsivity over a flat graphene device by combining the plasmonic effect and material densification. The crumpled structure also provides an exceptional 200% stretchability. The fabricated structure is mechanically robust, with no failure observed after 1000 cycles of stretching and releasing. The deformed 2D material system also provides a material platform for strain engineering of 2D materials. We created a 3D crumpled structure with a semiconducting 2D material, MoS2, to create inhomogeneous strain in the MoS2 lattice. This continuous strain change across the deformed structure induces a bandgap energy gradient, and therefore, provides efficient transport paths for photoexcited excitons in the deformed 2D lattice. We further demonstrated dynamic photoresponsivity modulation by structural modulation of a deformed 2D material, implying exciton drift modulation in a crumpled and flattened lattice structure. In conclusion, we have demonstrated effective strategies to create deformed 2D material systems with various levels of structural complexity, and related applications utilizing the unique topography and the strain gradient simultaneously created in the deformed lattice. We believe our approach to deforming 2D materials and achieving advanced functionalities contribute to the related research communities by demonstrating a way to extrinsically manipulate 2D materials' topography, and therefore modulate intrinsic properties.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-05-01","The student, Juyoung Leem, accepted the attached license on 2020-02-10 at 17:54.","The student, Juyoung Leem, submitted this Dissertation for approval on 2020-02-10 at 18:16.","This Dissertation was approved for publication on 2020-02-11 at 15:52.","DSpace SAF Submission Ingestion Package generated from Vireo submission #14867 on 2020-08-25 at 17:38:33","Made available in DSpace on 2020-08-27T00:46:48Z (GMT). No. of bitstreams: 2 LEEM-DISSERTATION-2020.pdf: 17273369 bytes, checksum: a90ffb7ca8fdc9502300d9946c1216e1 (MD5) LICENSE.txt: 4209 bytes, checksum: 2e2895d713d5718af88458e08f10b998 (MD5) Previous issue date: 2020-02-11","Embargo set by: Seth Robbins for item 115834 Lift date: 2022-08-27T00:46:59Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 115834 Lift date: 2022-08-27T00:50:22Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 115834 Lift date: 2022-08-27T00:51:40Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/108221"],"dc:language":["en"],"dc:rights":["Copyright 2020 Juyoung Leem"],"dc:subject":["2D Materials","Deformation","Mechanical self-assembly","Optoelectronics","Plasmonics"],"dc:title":["Mechanical self-assembly of deformed 2D materials for advanced functionalities"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:48Z"}