Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

Lee, Khang June; Kim, Daewon; Jang, Byung Chul; Kim, Da‐Jin; Park, Hamin; Jung, Dong Yun; Wang, Hong; Kim, Tae Keun; Choi, Yang‐Kyu; Choi, Sung‐Yool

doi:10.1002/adfm.201601850

Cited by 34 publications

(17 citation statements)

References 35 publications

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“…Leem et al reported 3D crumpled graphene–AuNPs hybrid structures for SERS applications using a mechanical self‐assembly strategy on a thermally activated polymer . Similarly, Lee et al fabricated a rippled graphene structure on a polystyrene substrate using a thermal rippling process and demonstrated the increased plasmonic coupling and higher density of the hot spots on the rippled nanostructure . Kumar et al presented a flexible SERS sensor by depositing Ag on structured polydimethylsiloxane using a Taro leaf as the template and achieved highly sensitive detection for malachite green .…”

Section: Introductionmentioning

confidence: 99%

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

et al. 2018

Adv Materials Technologies

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provide more hot spots, which are introduced by the electromagnetic mechanism (EM). By the virtue of their larger specific surface area and periodic structure, 3D SERS substrates can effectively amplify the optical field around metal nanoparticles (NPs), thereby enhancing the Raman signal. Moreover, the 3D structure of these substrates is beneficial for the enrichment of probe molecules around metal nanoparticles; as a result, one can still obtain a high Raman signal, even under an ultralow concentration. Consequently, an increasing number of researchers are now focusing on the design and fabrication of 3D SERS substrates.To make full use of the merits of the 3D structure, SERS substrates based on 2D materials and metal nanoparticles have been combined and proposed. [23,24] In these 3D SERS substrates, the 3D structure can fully utilize the 3D focal volume of the incident beam and increase the density of the metal nanoparticles. Furthermore, introduction of the 2D material can act as an atomically thick SERS substrate, [25] perfect absorbent layer of molecules, [26] excellent sub-nanometer spacer, [27] and passivation layer for metal, [28,29] and introduce enhancements via a chemical mechanism (CM). Previously, a 3D SERS substrate based on graphene covering a pyramid-shaped Au structure was reported to achieve high enhancement. [30] While the integration of graphene and pyramid-shaped Au was successfully implemented, this 3D SERS substrate was not flexible and did not meet with the requirements when detecting probe molecules on an arbitrary curvilinear surface.Therefore, transformation of these stiff 3D substrates into flexible structures via using various methods has been investigated extensively. Leem et al. reported 3D crumpled graphene-AuNPs hybrid structures for SERS applications using a mechanical self-assembly strategy on a thermally activated polymer. [31] Similarly, Lee et al. fabricated a rippled graphene structure on a polystyrene substrate using a thermal rippling process and demonstrated the increased plasmonic coupling and higher density of the hot spots on the rippled nanostructure. [32] Kumar et al. presented a flexible SERS sensor by depositing Ag on structured polydimethylsiloxane using a Taro leaf as the template and achieved highly sensitive detection for malachite green. [33] Moreover, to fabricate a flexible 3D SERS substrate, the transfer printing technique, [34] shadow Substrate design has attracted much interest in development of an effective surface enhanced Raman scattering (SERS) sensor. A flexible SERS substrate with excellent performance needs to be sensitive to details of the preparation process; this sensitivity represents a significant challenge for practical applications as opposed to laboratory research applications. Here, a 3D flexible plasmonic structure, AgNPs@MoS 2 /pyramidal polymer (polymethyl methacrylate), is fabricated using a simple and lowcost method. Using experiments and theoretical simulations, the SERS performance of the proposed substrate is assessed in terms of ...

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Section: Introductionmentioning

confidence: 99%

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

et al. 2018

Adv Materials Technologies

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“…Interestingly, we note that the enhancement factors are more pronounced at long wavelength. The maximum electric field intensity enhancement (| E | 2 /| E 0 | 2 ) created by monolayer MoS 2 for AuMAu and AgMAu reached up to ≈10 9 , which is much larger than previously reported metal nanostructures . Furthermore, both the AuMAu and AgMAu possessed the 3D bump structure and large amount of nanogaps among the assemblies, which is beneficial for adsorption of the analytes, therefore, making the analytes more accessible to the high density of hot spots.…”

Section: Resultsmentioning

confidence: 78%

“…Under the light illumination, the LSPR would produce a highly concentrated electromagnetic field (EF) near sharp asperities and the small gaps called “hot spots,” which can enhance orders of magnitude of the light intensity . The intensity of the “hot spots” is strongly sensitive to the gap size among the plasmonic nanostructures . Many efforts have been made to search for the efficient metallic nanostructures with optimum and uniformity gap size.…”

Section: Introductionmentioning

confidence: 99%

3D Hybrid Plasmonic Nanostructures with Dense Hot Spots Using Monolayer MoS₂ as Sub‐Nanometer Spacer

Jiang

Huo

et al. 2018

Adv Materials Inter

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some problems for the use of graphene. First, it has been demonstrated that the intensity of the EF generally increase as the gap decreases from 10 nm to 6.2 Å but fall off dramatically when the gap further decrease from 6.2 Å for the occurrence of quantum mechanical effects based on the results of the simulation and experiments. [16] The thickness of monolayer graphene is just 3.4 Å, which is so thin that the quantum mechanical electron tunneling emerge in a NP/G/NP or NP/G/ metal film structure. For such nanostructures, the electron tunneling can reduce the accumulation of opposite charges on the both sides of gap and further the EF in the "hot spots" would decrease. Second, the graphene film would tear and suspend inevitably in the transferring process and cannot be covered tightly on the top of the nanostructure with many sharp irregular shapes. [17] To realize the better plasmonic couplings, a kind of new spacer with superior optical property and stability should be introduced. Molybdenum disulfide (MoS 2 ), a semiconductor crystal, has a hexagonal crystal structure with the Mo atom in a trigonal biprism coordination sandwiched between two S atom layers. The MoS 2 films have drawn a lot of attention for applications in energy conversion, photocatalysis, and biochemical sensing for its low cost, good chemical performance, and high stability. [18][19][20][21] Consequently, many researches have reported MoS 2 combined with plasmonic structures and showed excellent photoelectrical properties recently. [22][23][24] In this work, we proposed a 3D hybrid structure using mono layer MoS 2 as spacer between adjacent metal NP. The direct growth of MoS 2 films on AuNP was first realized and the monolayer MoS 2 /AuNP was further obtained after the simple ultrasonic treatment. The AuNP and AgNP were used separately as the third metal nanostructure through the metal films sputtering and annealing process on the surface of the MoS 2 /AuNP. Then, the AuNP/MoS 2 /AuNP (AuMAu) and AgNP/MoS 2 /AuNP (AgMAu) hybrid assemblies were all fabricated and investigated, respectively. Although the hybrid structure seems to have some structural similarities with some works using graphene as spacer, there are several differences. First, the thickness of monolayer MoS 2 is around 6.5 Å close to the optimum gap size (6.2 Å), which is supposed to obtain the considerable enhancement of the EF. The monolayer MoS 2 can act as an insulating sub-nanometer spacer between two metal NP layers for its high vertical resistance and gap thickness to effectively prevent the emergence of the quantum Here, 3D hybrid plasmonic nanostructures using monolayer MoS 2 as subnanometer spacer with high density hot spots are fabricated. For the 3D hybrid assemblies, the hot spots exist not only on the 0.65 nm thick MoS 2 gap regions between large and small nanoparticles (NP) but also between small and small NP. The high-density hot spots induce prominently enhanced optical absorption, huge surface enhanced Raman scattering effect, excellent reproducibility, and ultr...

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“…Various strategies have been suggested for improving the photovoltaic performances of nanostructures by exploiting the plasmonic field enhancement. Among these, the vertically formed gap‐mode plasmon as in our vertically stacked electrode structure has a few advantages over the lateral plasmonic enhancement: 1) strong electric field excitation through and perpendicular to the MLG layer enhances the light absorption within the MLG, where photoexcited carriers are generated . The lateral plasmonic enhancement results in much weaker light–matter interaction only near the shallow region of the MLG layer in the vicinity of metal NPs, whereas the vertical gap‐mode plasmon occurs through the MLG spacer and covers the entire MLG with strong near‐fields (Figure b, for visual illustration).…”

Section: Resultsmentioning

confidence: 99%

Gap‐Mode Plasmon‐Induced Photovoltaic Effect in a Vertical Multilayer Graphene Homojunction

Lee

Kwon

Kim

et al. 2019

Advanced Optical Materials

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Gap‐mode plasmons that occur between metallic nanoparticles and metallic films separated by a thin spacer have been widely studied in the field of nano‐optics and plasmonics for enhancing the light–matter interaction of graphene and other two‐dimensional (2D) materials. However, efficient photovoltaic devices using such gap‐mode plasmons have not been achieved because of structural difficulties. Here, a gap‐mode plasmon‐induced asymmetric vertical homojunction photovoltaic device using multilayer graphene is presented. In this structure, the multilayer graphene acts both as a photo‐carrier generation layer and as a spacer for the gap‐mode plasmon. The optical absorption of graphene is further enhanced by the presence of gap‐mode plasmons, and the photoresponse time is extremely short because of the atomically short channel lengths across the vertical direction. The wavelength dependence of the gap‐mode plasmon is also investigated for three devices with different metal electrodes by photocurrent measurement at five different wavelengths and numerical simulations. The device strategies implemented in this work can enhance the performance of graphene‐based vertical photonic devices and can be applied to other 2D materials‐based photonic devices.

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Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

Cited by 34 publications

References 35 publications

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

3D Hybrid Plasmonic Nanostructures with Dense Hot Spots Using Monolayer MoS₂ as Sub‐Nanometer Spacer

Gap‐Mode Plasmon‐Induced Photovoltaic Effect in a Vertical Multilayer Graphene Homojunction

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Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

Cited by 34 publications

References 35 publications

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

Constructing 3D and Flexible Plasmonic Structure for High‐Performance SERS Application

3D Hybrid Plasmonic Nanostructures with Dense Hot Spots Using Monolayer MoS2 as Sub‐Nanometer Spacer

Gap‐Mode Plasmon‐Induced Photovoltaic Effect in a Vertical Multilayer Graphene Homojunction

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3D Hybrid Plasmonic Nanostructures with Dense Hot Spots Using Monolayer MoS₂ as Sub‐Nanometer Spacer