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

Arslan Shehzad M, Hoang Tien D, Waqas Iqbal M, Eom J, Park JH, Hwang C, Seo Y - Sci Rep (2015)

Bottom Line: From the experimental data, it was found that there were 6 different alignment orientations of the liquid crystal molecules on a single crystal substrate.We explain this result considering the bending of the tail of the liquid crystal molecules.Using this anchoring effect with six accurate discrete angles, a novel non-volatile display can be developed with micron-scale pixel size, due to the molecular level accuracy of the alignment.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology &Advanced Materials, HMC, and GRI, Sejong University, Seoul 143-747, South Korea.

ABSTRACT
We have studied the alignment of liquid crystal adsorbed onto graphene and hexagonal boron nitride by using a polarized optical microscope. From the experimental data, it was found that there were 6 different alignment orientations of the liquid crystal molecules on a single crystal substrate. This result has never been reported and is quite different from other previous results. As the hexagonal lattice has a threefold rotational symmetry, three different alignment orientations were expected, but our result seems counter-intuitive. We explain this result considering the bending of the tail of the liquid crystal molecules. Using this anchoring effect with six accurate discrete angles, a novel non-volatile display can be developed with micron-scale pixel size, due to the molecular level accuracy of the alignment.

No MeSH data available.


Optical microscopic images of the LC device between HOPG and rubbed layer.(a) Low magnification images confirm the presence of more than three colors including red, green and blue. (b–d) High magnification images of different positions of the same sample show many LC domains having different colors within a single-crystal substrate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4542626&req=5

f4: Optical microscopic images of the LC device between HOPG and rubbed layer.(a) Low magnification images confirm the presence of more than three colors including red, green and blue. (b–d) High magnification images of different positions of the same sample show many LC domains having different colors within a single-crystal substrate.

Mentions: The LC device was fabricated as shown in Fig. 3(b). HOPG on glass was spin coated with liquid crystal and a thin glass with unidirectional rubbed polyimide layer was placed on LC so that molecules will aligned unidirectional at the LC/polyimide interface. Alignment of the LC molecules in bottom side was dependant on the crystalline axis and LC preferential directions. The LC thickness was kept ~5 μm using spacers. Expected configurations of the LC directors are shown in Fig. 3(b) where the LC directors are twisted and a photonic band gap17 is induced. Optical images of HOPG/LC domains on the device are showed in Fig. 4 with low and high magnifications. The domains have different colors, which originated from different photonic band gaps corresponding to twisting angles due to the Bragg condition18, as well as a thickness gradient of LC. High magnification images (Fig. 4(b–d)) of different positions show that each domain with a discrete boundary has different color, confirming that the six preferential directions of LC exist in this device.


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

Arslan Shehzad M, Hoang Tien D, Waqas Iqbal M, Eom J, Park JH, Hwang C, Seo Y - Sci Rep (2015)

Optical microscopic images of the LC device between HOPG and rubbed layer.(a) Low magnification images confirm the presence of more than three colors including red, green and blue. (b–d) High magnification images of different positions of the same sample show many LC domains having different colors within a single-crystal substrate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542626&req=5

f4: Optical microscopic images of the LC device between HOPG and rubbed layer.(a) Low magnification images confirm the presence of more than three colors including red, green and blue. (b–d) High magnification images of different positions of the same sample show many LC domains having different colors within a single-crystal substrate.
Mentions: The LC device was fabricated as shown in Fig. 3(b). HOPG on glass was spin coated with liquid crystal and a thin glass with unidirectional rubbed polyimide layer was placed on LC so that molecules will aligned unidirectional at the LC/polyimide interface. Alignment of the LC molecules in bottom side was dependant on the crystalline axis and LC preferential directions. The LC thickness was kept ~5 μm using spacers. Expected configurations of the LC directors are shown in Fig. 3(b) where the LC directors are twisted and a photonic band gap17 is induced. Optical images of HOPG/LC domains on the device are showed in Fig. 4 with low and high magnifications. The domains have different colors, which originated from different photonic band gaps corresponding to twisting angles due to the Bragg condition18, as well as a thickness gradient of LC. High magnification images (Fig. 4(b–d)) of different positions show that each domain with a discrete boundary has different color, confirming that the six preferential directions of LC exist in this device.

Bottom Line: From the experimental data, it was found that there were 6 different alignment orientations of the liquid crystal molecules on a single crystal substrate.We explain this result considering the bending of the tail of the liquid crystal molecules.Using this anchoring effect with six accurate discrete angles, a novel non-volatile display can be developed with micron-scale pixel size, due to the molecular level accuracy of the alignment.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology &Advanced Materials, HMC, and GRI, Sejong University, Seoul 143-747, South Korea.

ABSTRACT
We have studied the alignment of liquid crystal adsorbed onto graphene and hexagonal boron nitride by using a polarized optical microscope. From the experimental data, it was found that there were 6 different alignment orientations of the liquid crystal molecules on a single crystal substrate. This result has never been reported and is quite different from other previous results. As the hexagonal lattice has a threefold rotational symmetry, three different alignment orientations were expected, but our result seems counter-intuitive. We explain this result considering the bending of the tail of the liquid crystal molecules. Using this anchoring effect with six accurate discrete angles, a novel non-volatile display can be developed with micron-scale pixel size, due to the molecular level accuracy of the alignment.

No MeSH data available.