Interstitially Mixed Self-Assembled Monolayers Enhance Electrical Stability of Molecular Junctions

Area of Science:

• Materials Science
• Molecular Electronics
• Nanotechnology

Background:

• Electrical breakdown is a major challenge in electronics, particularly in molecular electronics due to the delicate and defective nature of ultrathin molecular monolayers.
• Low intrinsic breakdown voltages of molecular monolayers limit device performance and reliability.

Purpose of the Study:

• To enhance the electrical stability of molecular-scale electronic devices using a novel self-assembled monolayer (SAM) strategy.
• To investigate the effect of interstitially mixed SAMs (imSAMs) on breakdown voltage and device functionality.

Main Methods:

• Development of a new approach, repeated surface exchange of molecules (ReSEM), to create imSAMs.
• Dilution of a sterically bulky matrix molecule (SC11BIPY rectifier) with a skinny reinforcement molecule (SC) using ReSEM.
• Combined experimental and simulation techniques to analyze the structure and electrical properties of imSAMs.

Main Results:

• ReSEM successfully created imSAMs with reinforcement molecules filling interstices between matrix molecules.
• imSAMs exhibited significantly enhanced breakdown voltage compared to traditional pure or mixed SAMs.
• Unprecedented bias-driven disappearance and inversion of rectification were observed due to enhanced stability.

Conclusions:

• imSAMs offer a promising strategy to overcome the instability limitations of SAMs in molecular electronics.
• The ReSEM method provides a pathway to create robust molecular electronic devices with improved performance and expanded functionalities.