Nano-confinement induced chain alignment in ordered P3HT nanostructures defined by nanoimprint lithography.

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Controlling polymer morphology and chain orientation is crucial for organic solar cells and field-effect transistors (OFETs).
• Existing bulk heterojunction structures have limitations in charge transport and optical properties.

Purpose of the Study:

• To utilize nanoimprint lithography for fabricating large-area, ordered nanostructures in poly(3-hexylthiophene) (P3HT).
• To simultaneously control the 3D chain alignment within these P3HT nanostructures.
• To investigate the impact of nanostructure geometry on chain orientation.

Main Methods:

• Nanoimprint lithography was employed to create P3HT nanostructures (gratings and pillars).
• Out-of-plane and in-plane grazing incident X-ray diffraction (GIXD) were used to analyze chain orientation.
• Analysis of pi-pi stacking and angular distribution within nanogratings.

Main Results:

• Nanoimprint lithography successfully fabricated ordered P3HT nanostructures with controlled 3D chain alignment.
• Vertical chain alignment was observed in both nanogratings and nanopillars.
• P3HT nanogratings exhibited pi-pi stacking along the grating direction with a +/-20 degree angular distribution, beneficial for OFETs.
• Chain alignment is attributed to nanoconfinement effects during nanoimprinting.

Conclusions:

• Nanoimprint lithography offers a viable method for precise control over polymer nanostructure geometry and chain alignment.
• The observed vertical chain alignment in P3HT nanostructures shows significant potential for improving charge transport and optical properties in organic electronic devices.
• The findings suggest a pathway towards high-performance organic solar cells and OFETs through controlled nanostructure fabrication.