Theoretical Study of a Molecular Resonant Tunneling Diode

Abstract

Density functional theory calculations are performed to explain the electrical behavior of a π-conjugated oligo(phenylene ethynylene) resembling a resonant tunneling diode. Results of this theoretical study are compatible with the assumptions that electron transport occurs through the lowest unoccupied molecular orbital, that the conduction barrier is determined by the molecule chemical potential, and that the molecule becomes charged as the external potential increases. We are able to explain the nonlinear character of the current-voltage characteristic of the molecule and its temperature dependence. The intrinsic controlledamplification feature of these molecules is indicated.

Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

“…This is different from the view in Ref. 4 and from other recent theoretical approaches to molecular conductivity, [20][21][22][23][24][25][26][27][28][29][30][31] but warranted by the recently discovered actual metal/ donor-acceptor-molecule/metal systems. Our approach also rests on recent broader theoretical [32][33][34][35][36] and experimental basis [37][38][39][40][41][42] for scanning tunneling microscopy ͑STM͒ of immobilized redox molecules with low-lying redox levels both in the ex situ, vacuum or air ambient, and in situ electrochemical modes.…”

“…The latter effect was also observed in an early report. 61 The mechanism of the molecular resonant tunnel diode of Reed and associates 18 proposed by Seminario et al 27,28 illustrates other features of importance in relation to nuclear dynamic effects. The current is mediated by the LUMO, the character of which changes drastically with the molecular charge.…”

“…Most of the approaches have focused on Green's function approaches to the electronic conductivity combined with electronic structure calculations of the molecular model systems. [23][24][25][26][27][28][29][30] Static broadening by the nuclear motion, 31 and geometry-optimization of differently charged electronic states 27,28 have also, however, been addressed. We shall return to this issue in the Discussion.…”

Tunneling of electrons via rotor–stator molecular interfaces: Combined ab initio and model study

“…Ever since the conductance of a molecular junction was experimentally quantified in the mechanically controllable break-junction experiments with benzene 1,4-dithiol SAMs onto golden electrodes [1], benzenebased molecules, also the subject of the present study, have been intensively investigated. Nonlinearity, negative differential resistance, conductance switching, found in various benzene derivatives are some of the many interesting properties that make these systems attractive for investigation from both, experimental and theoretical point of view [2,9,[13][14][15][16][17][18][19]. Mechanisms underlying the electron transport in these systems, which are predominated by the quantum-mechanical effects are complex and still a matter of debate.…”

Quantum Conductance Oscillations in Metal/Molecule/Metal Switches at Room Temperature

“…Our previous work demonstrated that conductance switching in Pt/stearic acid monolayer/Ti devices arises from the formation and dissolution of nanoscale conductance channels within the junction, likely due to electro-chemical reaction of the Pt and Ti electrodes [7,8]. This is in contrast to a number of molecule-specific switching mechanisms found in molecular devices, such as redox-induced configuration change of molecules [9--12], fluctuation in the bond between metal and molecules [13], or charge transfer [14,15]. The Pt/C18/Ti devices are thus nanoscale switches based on storage and manipulation of atoms, wherein the molecular layer acts as a porous medium through which atoms or ions can diffuse back and forth.…”