Temperature dependence of charge transport in solid-state molecular junctions based on oligo(phenylene ethynylene)s

Area of Science:

• Molecular electronics
• Materials science
• Condensed matter physics

Background:

• Advancing molecular electronics requires fabricating functional solid-state devices.
• Self-assembled monolayers (SAMs) are crucial for creating molecular junctions.
• Oligo(phenylene ethynylene)s (OPEs) and tetrathiafulvalene (TTF) are promising molecular components.

Purpose of the Study:

• To fabricate and characterize solid-state molecular junctions using OPEs and TTF-functionalized OPEs.
• To investigate the electrical transport properties and temperature dependence of these molecular devices.
• To explore the impact of molecular structure (linear vs. cross-conjugated) on device performance.

Main Methods:

• Fabrication of solid-state junctions using diamine-anchored OPE and OPE-TTF SAMs confined in micropores on gold substrates.
• Utilizing reduced graphene oxide (rGO) films for top contacts and interconnects in a double-junction configuration.
• Conducting electrical transport measurements under varying temperatures.

Main Results:

• Solid-state devices incorporating the TTF moiety (OPE3-TTF SAMs) exhibited higher conductance under ambient conditions compared to OPE3 SAMs.
• Electrical properties showed distinct temperature dependencies, with OPE3-TTF devices displaying temperature-dependent quantum interference.
• Linear-conjugated OPE3 devices did not exhibit quantum interference, highlighting the role of molecular structure.

Conclusions:

• The study successfully demonstrates the fabrication of functional molecular electronic devices with tailored properties.
• The incorporation of TTF enhances conductance, and molecular geometry influences quantum interference effects.
• This research contributes to understanding the temperature dependence of electrical properties in molecular devices, advancing functional molecular electronics.