HOMO–LUMO coupling: the fourth rule for highly effective molecular rectifiers

Thong, Aaron Zhenghui; Shaffer, Milo S. P.; Horsfield, Andrew P.

doi:10.1039/c7nr01680h

Cited by 19 publications

(16 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The redox activity of C 60 is relevant to opportunities as diverse as organic photovoltaic devices, 66 in vitro production of singlet oxygen for cancer treatment, 67 and molecular electronics. 68,69 As m-SWCNTs and graphene are ballistic conductors with excellent conductivity and current capacity, they are useful for transparent conducting films, 70,71 field emission devices, 72 and nanoelectronic circuitry. 73 On the other hand, the electronic properties and bandgaps of scSWCNTs make them useful for transistor devices, 74 solar cells, 75 and organic light-emitting diodes.…”

Section: Electronic Properties Of Neutral Carbon Nanomaterialsmentioning

confidence: 99%

Charged Carbon Nanomaterials: Redox Chemistries of Fullerenes, Carbon Nanotubes, and Graphenes

et al. 2018

Self Cite

View full text Add to dashboard Cite

Since the discovery of buckminsterfullerene over 30 years ago, sp 2 -hybridised carbon nanomaterials (including fullerenes, carbon nanotubes, and graphene) have stimulated new science and technology across a huge range of fields. Despite the impressive intrinsic properties, challenges in processing and chemical modification continue to hinder applications. Charged carbon nanomaterials (CCNs), formed via the reduction or oxidation of these carbon nanomaterials, facilitate dissolution, purification, separation, chemical modification, and assembly. This approach provides a compelling alternative to traditional damaging and restrictive liquid phase exfoliation routes. The broad chemistry of CCNs not only provides a versatile and potent means to modify the properties of the parent nanomaterial but also raises interesting scientific issues. This review focuses on the fundamental structural forms: buckminsterfullerene, single-walled carbon nanotubes, and single-layer graphene, describing the generation of their respective charged nanocarbon species, their interactions with solvents, chemical reactivity, specific (opto)electronic properties, and emerging applications. CONTENTS

show abstract

Section: Electronic Properties Of Neutral Carbon Nanomaterialsmentioning

confidence: 99%

Charged Carbon Nanomaterials: Redox Chemistries of Fullerenes, Carbon Nanotubes, and Graphenes

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…In this context, it is worth mentioning that Thong et al. already explained that such a type of crossover could be possible if coupling between electrode and molecule were strong . For the present device, couplings between Au−S and Fe−N at the junction are quite strong and, moreover, the two conjugated fragments are decoupled by a sigma bond.…”

Section: Resultsmentioning

confidence: 60%

Large Negative Differential Resistance and Rectification from a Donor–σ–Acceptor Molecule in the Presence of Dissimilar Electrodes

Koley

Chakrabarti

2018

Chemistry A European J

View full text Add to dashboard Cite

A multifunctional spin quantum device obtained by sandwiching 11-mercaptoundeca-2,4,8,10-tetraenenitrile, a donor-σ-acceptor molecule, between gold and iron electrodes is proposed. The device can act as a spin rectifier at lower bias and also exhibits negative differential resistance (NDR) after attaining a bias of 1.3 V. The rectification feature is quite prominent in the spin-up channel, with an appreciable rectification ratio of 68, whereas the NDR indicator, that is, the peak to valley ratio (≈10) of the current-voltage characteristics after 1.3 V, is also quite significant. To understand the origin of this in silico observation, nonequilibrium green's function based DFT calculations have been performed. Analyses reveal that both properties originate from the bias-independent energy offset between the frontier orbitals and electrode Fermi levels, popularly known as Fermi-level pinning. More precisely, rectification results from the Fermi-level pinning of the HOMO and LUMO with the gold and iron electrodes, respectively; the Fermi-level pinning forces a HOMO-LUMO crossover that helps to explain the origin of the NDR.

show abstract

“…The 4TPA-C 60 system has been shown to display resistance to HOMO/LUMO level inversion, similar to the behaviour of donor-acceptor systems reported by van Dyck and Ratner. The resistance towards level crossing has been previously attributed to charge reorganisation within the system, where charge transfer from donor to acceptor causes the LUMO to be pinned to the HOMO, thus effectively preventing inversion of the levels 13 , 15 . Unlike previous reports, it is found here that inversion of the levels in a 4TPA-C 60 junction does, in fact, occur, albeit at a much higher bias than what was previously investigated.…”

Section: Resultsmentioning

confidence: 99%

“…Although the original ansatz was designed with molecular rectification in mind, the proposed charge transport mechanisms should also give rise to negative differential resistance (NDR) features similar to those seen in quantum double-well resonant tunnelling devices (dw-RTDs) 1 , 9 , 10 . However, there have been conflicting reports on the bias response of these donor-acceptor systems, where crossing of the frontier states (and NDR) is only observed in some cases 11 , 12 , but not in others 13 – 15 . It is important to investigate these donor-acceptor systems at the point of resonance and beyond, in order to understand how to tailor these devices as RTDs or rectifiers.…”

Section: Introductionmentioning

confidence: 99%

Rectification and negative differential resistance via orbital level pinning

Thong

Shaffer

Horsfield

2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

A donor-acceptor system, 4-thiophenyl-azafulleroid (4TPA-C60), is investigated at the point of HOMO/LUMO resonance and beyond to understand how negative differential resistance (NDR) features may be observed in such systems. Our previous investigation showed that charge transfer between the occupied and unoccupied states at resonance hindered crossing of the HOMO and LUMO levels, thus preventing the formation of an NDR feature. In this work, it is shown that the negative differential resistance feature of 4TPA-C60 can be tailored based on the couplings at the metal/molecule interface. Ab initio calculations show that limited charge extraction from atomically sharp contacts results in a HOMO-LUMO pinning effect which delays the onset of the NDR feature. Subsequent unpinning of the states can only occur when additional charge extraction channels enter the bias window, highlighting an important role which non-frontier states play in charge transport. The proposed charge transfer mechanism is then exploited by introducing a fluorine atom into the C60 cage to tune the energies of the acceptor, and narrow the width of the current peak. These findings not only demonstrate the importance of the metal/molecule interface in the design of molecular electronic architectures but also serve to inform future design of molecular diodes and RTDs.

show abstract

HOMO–LUMO coupling: the fourth rule for highly effective molecular rectifiers

Cited by 19 publications

References 43 publications

Charged Carbon Nanomaterials: Redox Chemistries of Fullerenes, Carbon Nanotubes, and Graphenes

Charged Carbon Nanomaterials: Redox Chemistries of Fullerenes, Carbon Nanotubes, and Graphenes

Large Negative Differential Resistance and Rectification from a Donor–σ–Acceptor Molecule in the Presence of Dissimilar Electrodes

Rectification and negative differential resistance via orbital level pinning

Contact Info

Product

Resources

About