Electrically transmissive alkyne-anchored monolayers on gold

Area of Science:

• Materials Science
• Electrochemistry
• Surface Chemistry

Background:

• Self-assembled monolayers (SAMs) are crucial for molecular electronics.
• The interface between organic molecules and metal surfaces dictates electronic properties.
• Oligo(phenylene ethynylene)s offer tunable electronic characteristics.

Purpose of the Study:

• To investigate the electron transfer properties of alkynyl C-Au contacted SAMs.
• To explore the tunneling mechanism in molecular junctions.
• To compare the performance of different contacting groups in SAMs.

Main Methods:

• Preparation of well-ordered SAMs of 1,4-bis((4-ethynylphenyl)ethynyl)benzene on gold via self-assembly.
• Electrochemical measurements using redox probes ([Ru(NH3)6]3+, [Fe(CN)6]3-, ferrocenylmethanol).
• Analysis of voltage-dependent tunneling transitions.

Main Results:

• Formation of tightly-packed monolayer films with high surface coverage.
• Demonstration of facile electron transport through the alkynyl C-Au contacted SAM.
• Observation of a low voltage transition from direct to field emission tunneling (Vtrans = 0.51 V).
• Indication of a low tunneling barrier.

Conclusions:

• Alkynyl C-Au bonds facilitate efficient electron transfer in SAMs.
• The studied SAM presents a low barrier for electron transport, contrasting with other derivatives.
• The observed low transition voltage supports facile electron transport through the C-Au contacted SAM.