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Plasmonic phenomena in molecular junctions: principles and applications. Nat Rev Chem 2022; 6:681-704. [PMID: 37117494 DOI: 10.1038/s41570-022-00423-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2022] [Indexed: 11/08/2022]
Abstract
Molecular junctions are building blocks for constructing future nanoelectronic devices that enable the investigation of a broad range of electronic transport properties within nanoscale regions. Crossing both the nanoscopic and mesoscopic length scales, plasmonics lies at the intersection of the macroscopic photonics and nanoelectronics, owing to their capability of confining light to dimensions far below the diffraction limit. Research activities on plasmonic phenomena in molecular electronics started around 2010, and feedback between plasmons and molecular junctions has increased over the past years. These efforts can provide new insights into the near-field interaction and the corresponding tunability in properties, as well as resultant plasmon-based molecular devices. This Review presents the latest advancements of plasmonic resonances in molecular junctions and details the progress in plasmon excitation and plasmon coupling. We also highlight emerging experimental approaches to unravel the mechanisms behind the various types of light-matter interactions at molecular length scales, where quantum effects come into play. Finally, we discuss the potential of these plasmonic-electronic hybrid systems across various future applications, including sensing, photocatalysis, molecular trapping and active control of molecular switches.
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Bian Y, Liu S, Zhang Y, Liu Y, Yang X, Lou S, Wu E, Wu B, Zhang X, Jin Q. Distance-Dependent Plasmon-Enhanced Fluorescence of Submonolayer Rhodamine 6G by Gold Nanoparticles. NANOSCALE RESEARCH LETTERS 2021; 16:90. [PMID: 34021820 PMCID: PMC8141076 DOI: 10.1186/s11671-021-03546-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 05/13/2021] [Indexed: 05/22/2023]
Abstract
We investigate the fluorescence from submonolayer rhodamine 6G molecules near gold nanoparticles (NPs) at a well-controlled poly (methyl methacrylate) (PMMA) interval thickness from 1.5 to 21 nm. The plasmonic resonance peaks of gold NPs are tuned from 530 to 580 nm by the PMMA spacer of different thicknesses. Then, due to the plasmonic resonant excitation enhancement, the emission intensity of rhodamine 6G molecules at 562 nm is found to be enhanced and shows a decline as the PMMA spacer thickness increases. The variation of spectral intensity simulated by finite-difference time-domain method is consistent with the experimental results. Moreover, the lifetime results show the combined effects to rhodamine 6G fluorescence, which include the quenching effect, the barrier effect of PMMA as spacer layer and the attenuation effect of PMMA films.
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Affiliation(s)
- Yajie Bian
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006 Shanxi People’s Republic of China
| | - Shikang Liu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006 Shanxi People’s Republic of China
| | - Yuyi Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
| | - Yiting Liu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
| | - Xiaoyu Yang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
| | - Shitao Lou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
| | - E. Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006 Shanxi People’s Republic of China
| | - Botao Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
| | - Xiaolei Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006 Shanxi People’s Republic of China
| | - Qingyuan Jin
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241 People’s Republic of China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006 Shanxi People’s Republic of China
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Pal PP, Ramakrishna S, Seideman T. Emergence of Landauer transport from quantum dynamics: A model Hamiltonian approach. J Chem Phys 2018; 148:144707. [PMID: 29655338 DOI: 10.1063/1.5009815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Landauer expression for computing current-voltage characteristics in nanoscale devices is efficient but not suited to transient phenomena and a time-dependent current because it is applicable only when the charge carriers transition into a steady flux after an external perturbation. In this article, we construct a very general expression for time-dependent current in an electrode-molecule-electrode arrangement. Utilizing a model Hamiltonian (consisting of the subsystem energy levels and their electronic coupling terms), we propagate the Schrödinger wave function equation to numerically compute the time-dependent population in the individual subsystems. The current in each electrode (defined in terms of the rate of change of the corresponding population) has two components, one due to the charges originating from the same electrode and the other due to the charges initially residing at the other electrode. We derive an analytical expression for the first component and illustrate that it agrees reasonably with its numerical counterpart at early times. Exploiting the unitary evolution of a wavefunction, we construct a more general Landauer style formula and illustrate the emergence of Landauer transport from our simulations without the assumption of time-independent charge flow. Our generalized Landauer formula is valid at all times for models beyond the wide-band limit, non-uniform electrode density of states and for time and energy-dependent electronic coupling between the subsystems. Subsequently, we investigate the ingredients in our model that regulate the onset time scale of this steady state. We compare the performance of our general current expression with the Landauer current for time-dependent electronic coupling. Finally, we comment on the applicability of the Landauer formula to compute hot-electron current arising upon plasmon decoherence.
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Affiliation(s)
- Partha Pratim Pal
- Department of Chemistry, Northwestern University, Evanston, Illinois 60608, USA
| | - S Ramakrishna
- Department of Chemistry, Northwestern University, Evanston, Illinois 60608, USA
| | - Tamar Seideman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60608, USA
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Deckert-Gaudig T, Taguchi A, Kawata S, Deckert V. Tip-enhanced Raman spectroscopy - from early developments to recent advances. Chem Soc Rev 2018. [PMID: 28640306 DOI: 10.1039/c7cs00209b] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An analytical technique operating at the nanoscale must be flexible regarding variable experimental conditions while ideally also being highly specific, extremely sensitive, and spatially confined. In this respect, tip-enhanced Raman scattering (TERS) has been demonstrated to be ideally suited to, e.g., elucidating chemical reaction mechanisms, determining the distribution of components and identifying and localizing specific molecular structures at the nanometre scale. TERS combines the specificity of Raman spectroscopy with the high spatial resolution of scanning probe microscopies by utilizing plasmonic nanostructures to confine the incident electromagnetic field and increase it by many orders of magnitude. Consequently, molecular structure information in the optical near field that is inaccessible to other optical microscopy methods can be obtained. In this general review, the development of this still-young technique, from early experiments to recent achievements concerning inorganic, organic, and biological materials, is addressed. Accordingly, the technical developments necessary for stable and reliable AFM- and STM-based TERS experiments, together with the specific properties of the instruments under different conditions, are reviewed. The review also highlights selected experiments illustrating the capabilities of this emerging technique, the number of users of which has steadily increased since its inception in 2000. Finally, an assessment of the frontiers and new concepts of TERS, which aim towards rendering it a general and widely applicable technique that combines the highest possible lateral resolution and extreme sensitivity, is provided.
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Thoss M, Evers F. Perspective: Theory of quantum transport in molecular junctions. J Chem Phys 2018; 148:030901. [DOI: 10.1063/1.5003306] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael Thoss
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany
| | - Ferdinand Evers
- Institute of Theoretical Physics, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
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Zolotavin P, Evans C, Natelson D. Photothermoelectric Effects and Large Photovoltages in Plasmonic Au Nanowires with Nanogaps. J Phys Chem Lett 2017; 8:1739-1744. [PMID: 28365996 DOI: 10.1021/acs.jpclett.7b00507] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nanostructured metals subject to local optical interrogation can generate open-circuit photovoltages potentially useful for energy conversion and photodetection. We report a study of the photovoltage as a function of illumination position in single-metal Au nanowires and nanowires with nanogaps formed by electromigration. We use a laser scanning microscope to locally heat the metal nanostructures via excitation of a local plasmon resonance and direct absorption. In nanowires without nanogaps, where charge transport is diffusive, we observe voltage distributions consistent with thermoelectricity, with the local Seebeck coefficient depending on the width of the nanowire. In the nanowires with nanogaps, where charge transport is by tunneling, we observe large photovoltages up to tens of mV, with magnitude, polarization dependence, and spatial localization that follow the plasmon resonance in the nanogap. This is consistent with a model of photocurrent across the nanogap carried by the nonequilibrium, "hot" carriers generated upon plasmon excitation.
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Affiliation(s)
- Pavlo Zolotavin
- Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States
| | - Charlotte Evans
- Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States
| | - Douglas Natelson
- Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States
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Fung ED, Adak O, Lovat G, Scarabelli D, Venkataraman L. Too Hot for Photon-Assisted Transport: Hot-Electrons Dominate Conductance Enhancement in Illuminated Single-Molecule Junctions. NANO LETTERS 2017; 17:1255-1261. [PMID: 28112947 DOI: 10.1021/acs.nanolett.6b05091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We investigate light-induced conductance enhancement in single-molecule junctions via photon-assisted transport and hot-electron transport. Using 4,4'-bipyridine bound to Au electrodes as a prototypical single-molecule junction, we report a 20-40% enhancement in conductance under illumination with 980 nm wavelength radiation. We probe the effects of subtle changes in the transmission function on light-enhanced current and show that discrete variations in the binding geometry result in a 10% change in enhancement. Importantly, we prove theoretically that the steady-state behavior of photon-assisted transport and hot-electron transport is identical but that hot-electron transport is the dominant mechanism for optically induced conductance enhancement in single-molecule junctions when the wavelength used is absorbed by the electrodes and the hot-electron relaxation time is long. We confirm this experimentally by performing polarization-dependent conductance measurements of illuminated 4,4'-bipyridine junctions. Finally, we perform lock-in type measurements of optical current and conclude that currents due to laser-induced thermal expansion mask optical currents. This work provides a robust experimental framework for studying mechanisms of light-enhanced transport in single-molecule junctions and offers tools for tuning the performance of organic optoelectronic devices by analyzing detailed transport properties of the molecules involved.
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Affiliation(s)
- E-Dean Fung
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Olgun Adak
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Giacomo Lovat
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Diego Scarabelli
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Latha Venkataraman
- Department of Applied Physics and Applied Mathematics and ‡Department of Chemistry, Columbia University , New York, New York 10027, United States
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Galperin M. Photonics and spectroscopy in nanojunctions: a theoretical insight. Chem Soc Rev 2017; 46:4000-4019. [DOI: 10.1039/c7cs00067g] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Green function methods for photonics and spectroscopy in nanojunctions.
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Affiliation(s)
- Michael Galperin
- Department of Chemistry & Biochemistry
- University of California San Diego
- La Jolla
- USA
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