Large Built‐In Fields Control the Electronic Properties of Nanoscale Molecular Devices with Dipolar Structures. (17th April 2018)

• Record Type: Journal Article
• Authors: Van Dyck, Colin; Bergren, Adam J.
• Is Part Of: Advanced Electronic Materials. Volume 4:Number 5(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-04-17
• Subjects: built‐in fields -- dipoles -- Fermi level alignment -- molecular junctions -- theoretical investigation; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.201700656
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: 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. Abstract : In this theoretical study, a generic feature of asymmetric molecular junctions is introduced: the emergence of a large built‐in field. This field originates from permanent dipoles in the contacted molecules and is responsible for a large renormalization of the band alignment. Despite a high significance, this field has widely been neglected hitherto in the design and interpretation of device characteristics.