Bilayer molecular assembly at a solid/liquid interface as triggered by a mild electric field

Area of Science:

• Surface science
• Supramolecular chemistry
• Nanotechnology

Background:

• Controlling vertical molecular assembly is challenging in surface engineering.
• Existing methods often require high electric fields for structural transitions.

Purpose of the Study:

• To demonstrate electric field-induced formation of molecular bilayers.
• To investigate electric field-driven phase transformations in surface molecular assemblies.

Main Methods:

• Utilized a scanning tunneling microscope (STM) tip to apply a mild electric field (10^5 V/m) at a solid-liquid interface.
• Engineered a nanoporous network of trimesic acid on a graphite substrate.
• Manipulated polar molecules to form specific layered structures.

Main Results:

• A mild electric field successfully triggered the formation of a bilayer structure of polar molecules.
• The bilayer structure was reversibly transformed into a monolayer kagome structure by altering the electric field polarity.
• Achieved large-scale phase transformation in the perpendicular dimension.

Conclusions:

• Mild electric fields offer a precise method for controlling molecular assembly in the vertical direction.
• This approach provides new possibilities for tailoring surface molecular nanoarchitectures.
• Opens perspectives for advanced molecular device fabrication.