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Large Built‐In Fields Control the Electronic Properties of Nanoscale Molecular Devices with Dipolar Structures
Author(s) -
Dyck Colin,
Bergren Adam J.
Publication year - 2018
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201700656
Subject(s) - materials science , dipole , nanoscopic scale , asymmetry , nanotechnology , molecular electronics , layer (electronics) , field (mathematics) , voltage drop , molecular dynamics , condensed matter physics , chemical physics , voltage , molecule , computational chemistry , physics , quantum mechanics , chemistry , mathematics , pure mathematics
Large area molecular junctions are nanoscale materials made of a molecular layer sandwiched between two metal electrodes. In this study, a fundamental property of these systems is demonstrated: the emergence of a large built‐in field, typically as high as 10 9 V m −1 , and susceptible to appear in any junction possessing an asymmetry. This field originates from permanent dipoles in the contacted molecular layer and is responsible for a large renormalization of the band alignment in the junction. To illustrate this effect, a predictive theoretical characterization of two realistic gold‐thiolate‐based organic layers is carried out. The parameters leading to the emergence of the built‐in field are given and the very large renormalization effect is interpreted in terms of an applied voltage drop. Despite a high significance, this generic feature of molecular junctions has widely been neglected hitherto in the design and interpretation of molecular device characteristics. Built‐in fields provide a powerful way to achieve structure–property relationships in molecular junctions, by taking advantage of dipolar nanometric building blocks.