Nematic Liquid Crystal on a Two Dimensional Hexagonal Lattice and its Application.

Area of Science:

• Materials Science
• Surface Science
• Liquid Crystal Physics

Background:

• Graphene and hexagonal boron nitride (h-BN) are 2D materials with hexagonal lattices.
• Liquid crystals (LCs) exhibit unique optical properties influenced by surface alignment.
• Understanding LC alignment on 2D materials is crucial for advanced electronic applications.

Purpose of the Study:

• To investigate the alignment behavior of liquid crystals adsorbed onto graphene and hexagonal boron nitride substrates.
• To explore the relationship between substrate symmetry and LC molecular orientation.
• To identify potential applications arising from novel alignment phenomena.

Main Methods:

• Polarized optical microscopy was employed to observe and analyze the alignment of liquid crystal molecules.
• Experimental data was collected from liquid crystals adsorbed onto single crystal graphene and h-BN substrates.
• Analysis focused on identifying distinct molecular orientation angles.

Main Results:

• Six distinct alignment orientations of liquid crystal molecules were observed on single crystal substrates.
• This finding contradicts the expected three orientations based on the hexagonal lattice's threefold rotational symmetry.
• The observed phenomenon is explained by considering the bending of liquid crystal molecule tails, leading to a novel anchoring effect.

Conclusions:

• The study reveals an unexpected six-fold discrete angular alignment of liquid crystals on 2D hexagonal materials.
• This molecular-level alignment control, with six accurate angles, offers a new mechanism for display technology.
• A novel non-volatile display with micron-scale pixel resolution can be developed based on this anchoring effect.