Achieving Ultralow, Zero, and Inverted Tunneling Attenuation Coefficients in Molecular Wires with Extended Conjugation

Abstract

Molecular tunnel junctions are organic devices miniaturized to the molecular scale. They serve as a versatile toolbox that can systematically examine charge transport behaviors at the atomic level. The electrical conductance of the molecular wire that bridges the two electrodes in a junction is significantly influenced by its chemical structure, and an intrinsically poor conductance is a major barrier for practical applications toward integrating individual molecules into electronic circuitry. Therefore, highly conjugated molecular wires are attractive as active components for the next‐generation electronic devices, owing to the narrow highest occupied molecular orbital–lowest occupied molecular orbital gaps provided by their extended π‐building blocks. This article aims to highlight the significance of highly conductive molecular wires in molecular electronics, the structures of which are inspired from conductive organic polymers, and presents a body of discussion on molecular wires exhibiting ultralow, zero, or inverted attenuation of tunneling probability at different lengths, along with future directions.

Benzohexacene guide in accurate determination of field effect carrier mobilities in long acenes

“…Therefore, acenes are investigated for applications in organic light-emitting diodes (OLEDs), 9 organic light-emitting transistors (OLETs), 10 and organic thermoelectric generators, 11 and they are also studied as molecular wires. 12 However, unsubstituted acenes are highly insoluble due to strong intermolecular p-p interactions, which hinder their chemical synthesis and purication at the same time. Moreover, acenes are known for their sensitivity to oxygen and in addition, acenes longer than pentacene dimerize in solution, even in very dilute solutions, which makes thin lm and device fabrication unachievable.…”

“…Therefore, acenes are investigated for applications in organic light-emitting diodes (OLEDs), 9 organic light-emitting transistors (OLETs), 10 and organic thermoelectric generators, 11 and they are also studied as molecular wires. 12 …”

Anti-ohmic Nanoconductors: Myth, Reality and Promise

“…However, in recent years, molecular wires with unusual attenuation factors, such as β=0 (i.e., G independent of L) or even negative β values (i.e., G increasing with L) have become sparkle in the eyes of research community. [3][4][5] Such extraordinary wires exhibiting negative β values in phenomenological violation of the classical Ohm's law are called as anti-ohmic nanoconductors. This reversed exponential decay of conductance with length was first reported by Tada and Yoshizawa for nanographenes with zigzag edges.…”

Modulated Rectification of Carboxylate-Terminated Self-Assembled Monolayer Junction by Humidity and Alkali Metal Ions: The Coupling and Asymmetric Factor Matter

“…Molecular electronics − aims to miniaturize electronic devices based on molecular-scale active components, − and molecular electronic devices with different functions, such as diodes, switches, − and memories, − have been realized in recent years. Among them, molecular diodes are the basis of logic circuits, in which electrons flow through asymmetric organic molecules in only one direction .…”