Redox‐Induced Asymmetric Electrical Characteristics of Ferrocene‐Alkanethiolate Molecular Devices on Rigid and Flexible Substrates

Jeong, Hyunhak; Kim, Dongku; Wang, Gunuk; Park, Sung-Jun; Lee, Hanki; Cho, Kyungjune; Hwang, Wang Taek; Yoon, Myung Han; Jang, Yun Hee; Song, Hyunwook; Dong, Xiaopeng; Lee, Takhee

doi:10.1002/adfm.201303591

Cited by 74 publications

(80 citation statements)

References 64 publications

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“…1d). We believe that the mechanism of charge transport across these diodes is similar to that for diodes of S(CH 2 ) n Fc SAMs, which has been reported previously [29][30][31] . Briefly, with positive bias, the HOMO level falls below the Fermi levels of both electrodes and cannot participate in charge transport.…”

Section: Molecular Junctionssupporting

confidence: 82%

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On-chip molecular electronic plasmon sources based on self-assembled monolayer tunnel junctions

et al. 2016

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Molecular electronic control over plasmons offers a promising route for on-chip integrated molecular plasmonic devices for information processing and computing. To move beyond the currently available technologies and to miniaturize plasmonic devices, molecular electronic plasmon sources are required. Here, we report on-chip molecular electronic plasmon sources consisting of tunnel junctions based on self-assembled monolayers sandwiched between two metallic electrodes that excite localized plasmons, and surface plasmon polaritons, with tunnelling electrons. The plasmons originate from single, diffraction-limited spots within the junctions, follow power-law distributed photon statistics, and have well-defined polarization orientations. The structure of the self-assembled monolayer and the applied bias influence the observed polarization. We also show molecular electronic control of the plasmon intensity by changing the chemical structure of the molecules and by bias-selective excitation of plasmons using molecular diodes.S urface plasmon polaritons (SPPs) confine and enhance local electromagnetic fields near surfaces of metallic nanostructures at optical frequencies and have the ability to propagate along subdiffractive metallic waveguides, thereby opening up new perspectives for integrated optoelectronic circuits at the nanoscale 1-4 . However, almost all these applications use large external light sources such as monochromatic lasers. To minimize the size of the light sources and ultimately the size of the plasmonic devices, plasmons have been excited on-chip using electrically driven light sources such as (organic) light-emitting diodes (LEDs) 5-8 , laser diodes 9 , silicon spheres 10 and single carbon nanotubes 11 instead of bulky lasers. Surface plasmons have also been directly excited by tunnelling electrons in metal-insulator-metal junctions based on metal oxides 12-14 or scanning tunnelling microscopes (STMs) using vacuum or molecular tunnelling barriers [15][16][17][18][19][20][21][22][23][24][25] . During the tunnelling process, most of the electrons tunnel elastically, but some tunnel inelastically and couple to a plasmon mode. Direct excitation of plasmons by tunnelling electrons is attractive because not only is no background light generated but potentially it is also fast 26 (on the timescale of quantum tunnelling) as no slow electron-hole recombination processes are required as is the case for electroluminescent (nano)light sources 5-11 . Here, we report a direct electronic plasmon source based on molecular tunnel junctions operating via throughmolecular-bond tunnelling, where the plasmonic properties can be electrically controlled at the molecular level (without the need for optical antennas 27,28 ).In molecular electronic devices, the tunnelling barrier height is defined by the electronic energy levels of the molecule(s) bridging two electrodes. The tunnelling barrier width is defined by the length of the bridging molecule. Hence, the tunnelling gaps in molecular electronic devices are always exact...

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Section: Molecular Junctionssupporting

confidence: 82%

“…The tunnelling behaviour and electronic function (for example, rectification of currents [29][30][31] ) of the molecular junctions can be controlled by tuning the chemistry of the molecule. Combining molecular electronics with plasmonics may result in devices with novel properties that are otherwise difficult to realize 32,33 .…”

mentioning

confidence: 99%

On-chip molecular electronic plasmon sources based on self-assembled monolayer tunnel junctions

et al. 2016

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“…We have reported before molecular diodes based on SAMs of S(CH 2 ) 11 Fc in junctions of the form of Ag‐S(CH 2 ) 11 Fc//GaO x /eutectic alloy of gallium and indium (EGaIn) where “‐,” “//,” and “/” denote a covalent interaction, noncovalent interaction, and the interface between GaO x and EGaIn (Figure ), respectively. These diodes have large rectification ratios of 1.0 × 10 2 ; we have systematically studied the mechanism of charge transport across this diode in detail and our results have been confirmed by others . The HOMO is centered on the Fc unit and positioned asymmetrically inside the junction.…”

supporting

confidence: 81%

Stable Molecular Diodes Based on π–π Interactions of the Molecular Frontier Orbitals with Graphene Electrodes

et al. 2018

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In molecular electronics, it is important to control the strength of the molecule-electrode interaction to balance the trade-off between electronic coupling strength and broadening of the molecular frontier orbitals: too strong coupling results in severe broadening of the molecular orbitals while the molecular orbitals cannot follow the changes in the Fermi levels under applied bias when the coupling is too weak. Here, a platform based on graphene bottom electrodes to which molecules can bind via π-π interactions is reported. These interactions are strong enough to induce electronic function (rectification) while minimizing broadening of the molecular frontier orbitals. Molecular tunnel junctions are fabricated based on self-assembled monolayers (SAMs) of Fc(CH ) X (Fc = ferrocenyl, X = NH , Br, or H) on graphene bottom electrodes contacted to eutectic alloy of gallium and indium top electrodes. The Fc units interact more strongly with graphene than the X units resulting in SAMs with the Fc at the bottom of the SAM. The molecular diodes perform well with rectification ratios of 30-40, and they are stable against bias stressing under ambient conditions. Thus, tunnel junctions based on graphene with π-π molecule-electrode coupling are promising platforms to fabricate stable and well-performing molecular diodes.

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“…Previously, we have reported on the mechanism of charge transfer across molecular diodes with SAMs of SC 11 Fc on ultra-flat template-stripped silver-bottom electrodes (Ag TS ; henceforth left electrode) and EGaIn top electrodes (henceforth right electrode; a non-Newtonian liquid-metal alloy of eutectic In and Ga) [17][18][19] , including temperature-dependent J(V) measurements 20 (others have studied the mechanism rectification of SC n Fc SAMs in other types of junctions [21][22][23] ). This so-called 'EGaIn' technique is well established [24][25][26][27] and has been used in a wide range of physical-organic studies 20,[28][29][30][31][32][33] .…”

Section: Resultsmentioning

confidence: 99%

Controlling the direction of rectification in a molecular diode

et al. 2015

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A challenge in molecular electronics is to control the strength of the molecule-electrode coupling to optimize device performance. Here we show that non-covalent contacts between the active molecular component (in this case, ferrocenyl of a ferrocenyl-alkanethiol self-assembled monolayer (SAM)) and the electrodes allow for robust coupling with minimal energy broadening of the molecular level, precisely what is required to maximize the rectification ratio of a molecular diode. In contrast, strong chemisorbed contacts through the ferrocenyl result in large energy broadening, leakage currents and poor device performance. By gradually shifting the ferrocenyl from the top to the bottom of the SAM, we map the shape of the electrostatic potential profile across the molecules and we are able to control the direction of rectification by tuning the ferrocenyl-electrode coupling parameters. Our demonstrated control of the molecule-electrode coupling is important for rational design of materials that rely on charge transport across organic-inorganic interfaces.

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Redox‐Induced Asymmetric Electrical Characteristics of Ferrocene‐Alkanethiolate Molecular Devices on Rigid and Flexible Substrates

Cited by 74 publications

References 64 publications

On-chip molecular electronic plasmon sources based on self-assembled monolayer tunnel junctions

On-chip molecular electronic plasmon sources based on self-assembled monolayer tunnel junctions

Stable Molecular Diodes Based on π–π Interactions of the Molecular Frontier Orbitals with Graphene Electrodes

Controlling the direction of rectification in a molecular diode

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