Electric Field Control of Molecular Charge State in a Single-Component 2D Organic Nanoarray

Abstract

Quantum dots (QD) with electric-field-controlled charge state are promising for electronics applications, e.g., digital information storage, single-electron transistors and quantum computing. Inorganic QDs consisting of semiconductor nanostructures or heterostructures often offer limited control on size and composition distribution, as well as low potential for scalability and/or nanoscale miniaturization. Owing to their tunability and self-assembly capability, using organic molecules as building nano-units can allow for bottom-up synthesis of two-dimensional (2D) nanoarrays of QDs. However, 2D molecular self-assembly protocols are often applicable on metals surfaces, where electronic hybridization and Fermi level pinning can hinder electric-field control of the QD charge state. Here, we demonstrate the synthesis of a single-component self-assembled 2D array of molecules [9, 10-dicyanoanthracene (DCA)] that exhibit electric-field-controlled spatially periodic charging on a noble metal surface, Ag(111). The charge state of DCA can be altered (between neutral and negative), depending on its adsorption site, by the local electric field induced by a scanning tunneling microscope tip. Limited metal-molecule interactions result in an effective tunneling barrier between DCA and Ag(111) that enables electric-field-induced electron population of the lowest unoccupied molecular orbital (LUMO) and hence charging of the molecule. Subtle site-dependent variation of the molecular adsorption height translates into a significant spatial modulation of the molecular polarizability, dielectric constant and LUMO energy level alignment, giving rise to a spatially dependent effective molecule-surface tunneling barrier and likelihood of charging. This work offers potential for high-density 2D self-assembled nanoarrays of identical QDs whose charge states can be addressed individually with an electric field.

References in corpus (9)

• Quantum Computation with Quantum Dots
• A single-electron transistor made from a cadmium selenide nanocrystal
• Quantum phase transition in a single-molecule quantum dot
• Gate-Controlled Ionization and Screening of Cobalt Adatoms on a Graphene Surface
• Two-dimensional band structure in honeycomb metal-organic frameworks
• Gating a single-molecule transistor with individual atoms
• Gating the charge state of a single molecule by local electric fields
• Iron-based trinuclear metal-organic nanostructures on a surface with local charge accumulation
• Single electron gating of topological insulators

Cited by in corpus (5)

• Manifestation of strongly correlated electrons in a 2D kagome metal-organic framework
• Selective Activation of Aromatic C-H Bonds Catalyzed by Single Gold Atoms at Room Temperature
• Synthesis and Local Probe Gating of a Monolayer Metal-Organic Framework
• Local gate control of Mott metal-insulator transition in a 2D metal-organic framework
• Upper Bound Estimate of the Electronic Scattering Potential of a Weakly Interacting Molecular Film on a Metal