Moon-gyu Lee

Directed Assembly of High Molecular Weight Block Copolymers: Highly Ordered Line Patterns of Perpendicularly Oriented Lamellae with Large Periods

The directed assembly of block copolymer nanostructures with large periods exceeding 100 nm remains challenging because the translational ordering of long-chained block copolymer is hindered by its very low chain mobility. Using a solvent-vapor annealing process with a neutral solvent, which was sequentially combined with a thermal annealing process, we demonstrate the rapid evolution of a perpendicularly oriented lamellar morphology in high molecular weight block copolymer films on neutral substrate. The synergy with the topographically patterned substrate facilitated unidirectionally structural development of ultrahigh molecular weight block copolymer thin films-even for the structures with a large period of 200 nm-leading to perfectly guided, parallel, and highly ordered line-arrays of perpendicularly oriented lamellae in the trenched confinement. This breakthrough strategy, which is applicable to nanolithographic pattern transfer to target substrates, can be a simple and efficient route to satisfy the demand for block copolymer assemblies with larger feature sizes on hundreds of nanometers scale.

Rapid structural reorganization in thin films of block copolymer self-assembly

In the present study, the thin films of a symmetric polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) were prepared on a neutral substrate and subjected to solvent annealing, sequentially coupled with thermal annealing for a short time. For this process, a P(S-r-MMA)-grafted substrate was used for surface neutrality to the PS and PMMA blocks. During solvent annealing with PMMA-selective acetone vapor, the block copolymer (BCP) films show a predominantly parallel orientation of the cylindrical PS microdomains over the underlying perpendicular PS cylinders on the substrate. Sequential thermal annealing of the BCP films for a short time led to efficient structural reorganization to an equilibrium morphology with the perpendicular orientation of the lamellar microdomains. This approach suggests a simple and useful route for directing the orientation of microdomain arrays in the thin films of BCP self-assembly.

Integral imaging with reduced color moire pattern by using a slanted lens array

In this paper, we propose a color moire pattern reduction method in integral three-dimensional imaging by slanting the lens array. The color moire patterns are examined as varying the slanted angles between the lens array and the display panel for choosing the angles for which the pattern is reduced. However, it is difficult to expect the tendency of the pattern. We simulate the color moire pattern on the assumption of ray optics and find out the angle where the moiré is reduced. With the proposed technique clear three dimensional images can be displayed. The explanation of the proposed method will be provided, and the simulation results will be shown. Finally, experimental results will verify the proposed method.

Novel wide viewing liquid crystal display with improved off-axis image quality in a twisted nematic configuration

We developed a novel twisted nematic (TN) liquid crystal display (LCD) having wide viewing angle characteristics through the reduction of the residual liquid crystal phase retardation at oblique angles using an embedded diffusing unit. Compared to a conventional TN panel, this embedded approach provides extended isocontrast contours by more than ±10 deg at a contrast ratio of 100:1 along the horizontal direction and a wide region free of grayscale inversion by a factor of 2 along the vertical direction. Moreover, the off-axis image distortions in our novel LCD are improved by 50% compared to those in a film-compensated TN LCD.

46.1: Directivity Enhanced BLU for Edge-type Local Dimming

In this paper, we suggest an elegant and cost-effective Backlight Unit which is slim and has locally confined light needed for 1-dimensional local dimming and scanning. We fabricated LGP with micro-structures patterned by CO2 Laser. Lights from LGP are well distributed and uniform with density control of micro-patterns because they are continuous over the whole region of LGP. With one dimensional local dimming, we obtained 43% power-saving effect and contrast ratio of 11400:1 without any hot spot and the artifact.