Effect of binding group on hybridization across the silicon/aromatic-monolayer interface

Toledano, Tal; Garrick, Rachel; Sinai, Ofer; Bendikov, Tatyana; Haj-Yahia, Abd-Elrazek; Lerman, Keti; Alon, Hadas; Sukenik, Chaim N.; Vilan, Ayelet; Kronik, Leeor

doi:10.1016/j.elspec.2015.05.019

Cited by 9 publications

(32 citation statements)

References 65 publications

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“…This trend agrees with the gas-phase DFT calculations, although, as expected, the differences between IPs derived from UPS are smaller than the gas-phase DFT differences. Stabilization of energy levels upon adsorption (i.e., from gas-phase to surface-adsorbed species) is well-documented and attributed to surface polarization effects (50), dipole-dipole interactions between peptides in the monolayer (51,52), and molecule-substrate charge rearrangement (53,54). However, the work functions of the peptide monolayers on Au hardly change with Trp position (SI Appendix, Fig.…”

Section: Significancementioning

confidence: 99%

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping

Guo

Refaely-Abramson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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113

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Charge migration for electron transfer via the polypeptide matrix of proteins is a key process in biological energy conversion and signaling systems. It is sensitive to the sequence of amino acids composing the protein and, therefore, offers a tool for chemical control of charge transport across biomaterial-based devices. We designed a series of linear oligoalanine peptides with a single tryptophan substitution that acts as a "dopant," introducing an energy level closer to the electrodes' Fermi level than that of the alanine homopeptide. We investigated the solid-state electron transport (ETp) across a selfassembled monolayer of these peptides between gold contacts. The single tryptophan "doping" markedly increased the conductance of the peptide chain, especially when its location in the sequence is close to the electrodes. Combining inelastic tunneling spectroscopy, UV photoelectron spectroscopy, electronic structure calculations by advanced density-functional theory, and dc current-voltage analysis, the role of tryptophan in ETp is rationalized by charge tunneling across a heterogeneous energy barrier, via electronic states of alanine and tryptophan, and by relatively efficient direct coupling of tryptophan to a Au electrode. These results reveal a controlled way of modulating the electrical properties of molecular junctions by tailormade "building block" peptides. oligopeptide | electron transport | self-assembled monolayer | inelastic electron tunneling spectroscopy | doping E lectron transfer (ET) processes taking place between prosthetic groups across the polypeptide matrices of proteins (1-3) have been extensively explored by, e.g., time-resolved photolysis (4, 5), pulse radiolysis (6, 7), scanning tunneling microscopy (8, 9), electrochemical methods (10-12), and by theoretical studies (13-16). The surprisingly fast and efficient ET over considerable distances (up to ∼25 Å) (17) via peptide matrices in proteins suggests possible development of peptide-and protein-based bioelectronics with diverse functionality and relative ease of modification (18,19). Studying electron transport (ETp) via solid-state molecular junctions represents an approach, bridging the study of basic ET-related phenomena and electronic devices, where measuring ET rates as a function of an electrochemical driving force is replaced by measuring current across molecular junctions as a function of an applied electrical voltage (20). Combining the concepts and methods of molecular electronics such as currentvoltage (I-V) line-shape analysis (21, 22), temperature-dependent measurements (23, 24), and electronic spectroscopy techniques (25-27) may yield new insights into the mechanism of ETp across the peptide matrix of proteins (28-30) and pave the road to peptide-and protein-based electronic devices for switching, rectification, and memory (18, 31).ETp via homopeptides has been investigated, probing the roles of specific amino acid residues, their protonation, and secondary structure (29,32). Synthetic heteropeptides with defined compositi...

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Section: Significancementioning

confidence: 99%

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping

Guo

Refaely-Abramson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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113

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“…In molecular junctions, controlling the energy level alignment is a critical issue . In this context, the molecule–electrode interaction strength, Γ (in eV), is one of the critical parameters because it determines the tunneling rate across the junction and the level of hybridization of the molecular orbitals with the orbitals from the electrodes . Often molecules are attached to electrodes via covalent interactions to achieve strong coupling.…”

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confidence: 99%

“…Often molecules are attached to electrodes via covalent interactions to achieve strong coupling. Strong coupling results in high tunneling rates, and the molecular levels follow the changes in the Fermi levels of the electrodes under bias, but it also causes broadening of the molecular energy levels ( Figure a) . This molecular energy level broadening is often undesirable as it reduces the offset in energy between molecular orbitals and the Fermi level of the electrode ( δE ME in eV), which can cause leakage currents and, for instance, lower the performance of molecular diodes .…”

mentioning

confidence: 99%

“…This molecular energy level broadening is often undesirable as it reduces the offset in energy between molecular orbitals and the Fermi level of the electrode ( δE ME in eV), which can cause leakage currents and, for instance, lower the performance of molecular diodes . In contrast, attaching the molecules via physisorption, or decoupling functional groups via alkyl chain tethers, results in weak coupling, i.e., small values of Γ , and leaves the molecular orbitals narrow and confined on the molecule but results in low tunneling rates because the orbitals cannot efficiently follow the changes in the Fermi levels under bias . Thus, for many applications, it is important to maximize Γ to induce electronic function while keeping the molecular orbitals confined to the molecule (intermediate coupling regime), but this goal is difficult to achieve due to the tradeoff between Γ , δE ME , and molecular energy level broadening .…”

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confidence: 99%

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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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“…15,16 The nature of the connection to silicon for electronic applications is critical as the chemical identity of this linkage can have profound effects on the electronics of the underlying semiconductor. 17,18 For instance, the junction resistance of silicon-based solar generators can be reduced by surface functionalization, thus optimizing the electrical transport throughout the system. 5 The thickness of a self-assembled monolayer (SAM) or the length of molecular wires on a functionalized surface will also have a significant impact on electron-transport mechanisms.…”

Section: ■ Introductionmentioning

confidence: 99%

Expanding the Repertoire of Molecular Linkages to Silicon: Si–S, Si–Se, and Si–Te Bonds

Liu

Buriak

2016

ACS Appl. Mater. Interfaces

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Effect of binding group on hybridization across the silicon/aromatic-monolayer interface

Cited by 9 publications

References 65 publications

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping

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

Expanding the Repertoire of Molecular Linkages to Silicon: Si–S, Si–Se, and Si–Te Bonds

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