Multilevel nanoimprint lithography with a binary mould for plasmonic colour printing.

Area of Science:

• Nanotechnology
• Materials Science
• Optics

Background:

• Plasmonic resonances offer pigment-free colouration for manufacturing.
• Metal-insulator-metal (MIM) configurations for plasmonic colour depend on geometry and vertical gap size.
• Conventional fabrication methods like electron beam lithography (EBL) struggle to control this critical gap parameter.

Purpose of the Study:

• To demonstrate a straightforward method for producing plasmonic colour using UV-assisted nanoimprint lithography (NIL).
• To show control over the vertical gap distance in plasmonic structures via nanofluidic polymer behaviour and mould design.
• To explore an additional avenue for colour control beyond conventional transverse dimension tailoring.

Main Methods:

• Utilizing UV-assisted nanoimprint lithography (NIL) with a simple binary mould.
• Harnessing nanofluidic behaviour of polymer resist through strategic mould design to control vertical gap distance.
• Introducing microcavities in the mould for fixed gap size control.

Main Results:

• Achieved precise control over the vertical gap in plasmonic structures during a single NIL print.
• Demonstrated wide colour coverage across the CIE 1931 XY colour space by controlling structural dimensions and gap size.
• Successfully produced fixed gap sizes using complementary microcavities in the mould design.

Conclusions:

• NIL offers a simple and effective method for controlling vertical gap dimensions in plasmonic structures.
• This technique provides an additional degree of freedom for tunable structural colouration.
• The method has potential applications in high-density memory, biosensors, and advanced manufacturing.