Subdiffraction Multiphoton Polymerization of PEDOT

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Direct laser writing via multiphoton polymerization (MPP) is limited to specific polymer types.
• Existing methods struggle with fabricating sub-100 nm structures with high resolution.

Purpose of the Study:

• To demonstrate a novel application of a photoinitiator (DETC) for direct laser writing of PEDOT nanostructures.
• To achieve sub-100 nm resolution in direct laser writing using visible light.

Main Methods:

• Utilized ketocoumarin 7-diethylamino-3-thenoylcoumarin (DETC) as a photoinitiator for oxidative step-growth polymerization of EDOT.
• Employed two subdiffractional MPP approaches: slow scanning with oxygen influx and STED-inspired transient state absorption depletion lithography.
• Analyzed resulting nanostructures using Raman spectroscopy.

Main Results:

• Successfully fabricated PEDOT nanostructures with feature sizes down to 65 nm using visible light.
• Achieved linewidths of 65 nm at 2.5 μm/s (slow scanning) and 105 nm at 100 μm/s (STED-inspired).
• Raman spectroscopy indicated that conductivity in PEDOT wires correlates with the formation of graphitic phases.

Conclusions:

• DETC effectively initiates oxidative step-growth polymerization of EDOT for direct laser writing of sub-100 nm PEDOT nanostructures.
• Subdiffractional MPP techniques, including oxygen-mediated and STED-inspired methods, enable high-resolution fabrication of conductive polymers.
• The formation of graphitic phases is crucial for achieving conductivity in MPP-written PEDOT wires.