title: Harnessing Quantum Interference in Molecular Dielectric Materials.
abstract: We investigate the relationship between dielectric response and charge transport in molecule-based materials operating in the quantum coherent regime. We find that quantum interference affects these observables differently, for instance, allowing current passing through certain materials to be reduced by orders of magnitude without affecting dielectric behavior (or band gap). As an example, we utilize ab initio electronic structure theory to calculate conductance and dielectric constants of cross-conjugated anthraquinone (AQ)-based and linearly conjugated anthracene (AC)-based materials. In spite of having nearly equal fundamental gaps, electrode bonding configurations, and molecular dimensions, we find a ∼1.7 order of magnitude (∼50-fold) reduction in the conductance of the AQ-based material relative to the AC-based material, a value in close agreement with recent measurements, while the calculated dielectric constants of both materials are nearly identical. From these findings, we propose two molecular materials in which quantum interference is used to reduce leakage currents across a ∼25 Å monolayer gap with dielectric constants larger than 4.5.
authors.affiliation: †Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Bergfield
authors.affiliation: †Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Henry M
authors.initials: HM
authors.lastname: Heitzer
authors.affiliation: †Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Colin
authors.initials: C
authors.lastname: Van Dyck
authors.affiliation: †Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
authors.affiliation: †Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ratner
keywords: cross-conjugated polymers; density functional theory; molecular dielectric material; nonequilibrium quantum transport; quantum interference