Polymer-stabilized Blue Phase Research Articles

Polarization-independent rapidly responding phase grating based on hybrid blue phase liquid crystal

This work demonstrates a polymer-stabilized blue phase (PSBP) liquid crystal phase grating, which is made of hybrid PSBPs with two different Kerr constants. The Kerr constant of a PSBP is related to the morphology of the polymer network which can be controlled by the phase separation temperature. Owing to the non-patterned electrode and the optical isotropy of the PSBP, the diffraction effect can be completely switched off when the voltage is absent. The diffraction intensity increases when a uniform applied electrical field induces the phase difference in the hybrid PSBP. The phase grating is completely independent of the polarization of the incident light. Furthermore, the response time to switching is in the sub-millisecond range.

Low voltage and high contrast blue phase liquid crystal with red-shifted Bragg reflection

We demonstrated a low voltage and high contrast polymer-stabilized blue phase liquid crystal (BPLC) by shifting the Bragg reflection to a red wavelength. To retain high contrast ratio, a left-handed BPLC is sandwiched between a right-handed circular polarizer and a left-handed circular analyzer. The driving voltage is reduced by 35% as compared to that of a transparent BPLC, while keeping submillisecond response time. The proposed approach would accelerate the emergence of BPLC for next-generation display and photonic applications.

Polymer-stabilized nanoparticle-enriched blue phase liquid crystals

Electro-optical switching with low voltage, no hysteresis and fast response speed is achieved in polymer-stabilized nanoparticle-enriched blue phase liquid crystals with a wide temperature range, and it is found that the benefits from the combined method are more than from the simple addition of polymer stabilization and nanoparticle dispersion.

Figure of Merit of Polymer-Stabilized Blue Phase Liquid Crystals

A figure of merit (FoM), defined as the ratio of Kerr constant to response time, is used to characterize and compare the electro-optic performance of polymer-stabilized blue phase liquid crystals (BPLCs). Increasing the dielectric anisotropy of LC host enhances Kerr constant and lowers the operation voltage, but its associated high viscosity dramatically increases the response time. As a result, the FoM may not be necessarily higher. For a given BPLC device, an optimal temperature exists where FoM reaches maximum. The proposed FoM provides useful guidelines for optimizing BPLCs for display and photonic applications.

Polymer-stabilized supercooled blue phase

We report a method to prepare a polymer-stabilized liquid-crystal blue phase that is effective over a wide range of temperature. There are two main key points about this method: (1) A precursor solution is injected into the cell at an enough high temperature above the blue phase–isotropic phase transition point, and (2) a photo-polymerization process with a deeply supercooled blue phase of the precursor solution stabilizes the phase. Thus, a polymer-stabilized “supercooled” blue phase is achieved through photo-polymerization over a wide range of temperature. The proposed method will be very beneficial for manufacturing blue-phase-mode liquid crystal displays.

An experimental investigation of electrically induced-birefringence of Kerr effect in polymer-stabilized blue phase liquid crystals resulting from orientations of liquid crystals

The electrically induced-birefringence (EIB) of Kerr effect of polymer-stabilized blue phase liquid crystals (PSBP-LCs) is experimentally investigated by discussing the orientations of liquid cryastal (LC) molecules. The results show that the EIB of Kerr effect of PSBP-LCs mainly results from the orientations of LC molecules when the voltage is larger than the voltage of disappearance of the lattice deformation; otherwise, lattice deformation is also involved in the contribution of EIB besides the orientations of LC molecules. This study proves that the orientations of liquid crystals indeed play roles in the EIB of Kerr effect in PSBP-LCs.

PA45 高分子安定化ブルー相の安定性および電気光学特性に及ぼすモノマー分子構造の影響(ソフトマター,ポスター発表,2012年日本液晶学会討論会)

PA45 高分子安定化ブルー相の安定性および電気光学特性に及ぼすモノマー分子構造の影響(ソフトマター,ポスター発表,2012年日本液晶学会討論会)

Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles

We demonstrate a hysteresis-free polymer-stabilized blue phase liquid crystals (PSBP-LCs) using thermal recycles by means of enlarging the domain size of PSBP-LC and improving the uniformity of the crystal orientations of PSBP-LC. The crystal growth of PSBP-LCs bases on a competition between the heterogeneous nucleation and the homogeneous nucleation is also demonstrated and discussed. This study opens a new window for understanding the hysteresis of the PSBP-LC and assisting in designing many PSBP-LC-based photonic devices, such as displays, electro-optical switches, and electrically tunable focusing LC lenses.

Polymer-stabilized blue phase liquid crystal with a negative Kerr constant

A polymer-stabilized blue-phase liquid crystal (BPLC) with a negative Kerr constant is reported. In a voltage-on state, the double-twist BPLC molecules within the lattice cylinders are reoriented perpendicular to the applied electric field because of their negative dielectric anisotropy. As a result, the induced birefringence has a negative value, which leads to a negative Kerr constant. The negative sign of Kerr constant is experimentally validated by using a quarter-wave plate and a vertical field switching cell. Such a BPLC shows a negligible (~1%) hysteresis and fast response time (~1ms) at the room temperature, although its Kerr constant is relatively small because the employed host has a small Δe.

Low Voltage and High Transmittance Polymer-Stabilized Blue-Phase Liquid Crystal Device by Combined In-Plane and Oblique Electric Field along the Horizontal Direction

We propose a polymer-stabilized blue-phase liquid crystal (PS-BPLC) device with high transmittance and low driving voltage by designing the electrode structure. The electrodes are comprised with two interdigitated bottom pixel electrodes with opposite polarities and a top common electrode with 0 V, which is placed in the middle of the two bottom electrodes. Since these electrode structures could generate a strong horizontal electric field and induce a high Kerr effect, we could realize a lower driving voltage (30 V) and higher transmittance characteristics (20%) than those of conventional PS-BPLC cells with an in-plane switching electrode structure.

The influence of cyano compound on liquid crystal blue phase range

Liquid crystal blue phase (BP) is interesting for fast light modulators and tunable photonic crystals. In this study the influence of mixture composition on the thermal stability of BP was investigated, especially the influence of cyano compound addition. The relationship between polymer stabilization possibility and cyano dopant was examined, too. It was shown that the cyano compound is not necessary to create blue phase and has no effect on polymer stabilization of blue phase. Full Text: PDF References H. Kikuchi, M. Yokota, Y. Hisakado, H. Yang, T. Kajiyama, "Polymer-stabilized liquid crystal blue phases", Nature Materials 1, 64 (2002) CrossRef H. Yoshida, Y. Tanaka, K. Kawamoto, H. Kubo, T. Tsuda, A. Fuji, S. Kuwabata, H. Kikuchi, M. Ozaki, "Optical and Thermal Characteristics of Nd:LuVO 4 Grown by Floating Zone Method", Appl. Phys. Express, 2, 12501 (2009) CrossRef K. Z. Zheng, D. Shen, P. Huang, "Wide blue phase range of chiral nematic liquid crystal doped with bent-shaped molecules", New J. Phys., 12, 113018 (2010). CrossRef H. Kikuchi, H. Higuchi, "Fast Electro-Optical Switching in Polymer-Stabilized Liquid Crystalline Blue Phases for Display Application", SID07 Digest, 38, 1737-1740 (2007) CrossRef J. P. Sethna, in Theory and Applications of Liquid Crystals (edited by J. L. Ericksen and D. Kinderlehrer) (Springer-Verlag,1987), p. 305 CrossRef P.P. Crooker, in Chirality in Liquid Crystals (edited by H.S. Kitzerow and C. Bahr)186-222 (Springer, New York, 2001) CrossRef P. R. Gerber, "Electro-Optical Effects of a Small-Pitch Blue-Phase System", Mol. Cryst. Liq. Cryst., 116, 197 (1985) CrossRef K. M. Chen, S. Gauza, H. Xianyu, S. T. Wu, "Submillisecond Gray-Level Response Time of a Polymer-Stabilized Blue-Phase Liquid Crystal", J. Display Technol., 6, 49 (2010) CrossRef S. T. Wu, D. K. Yang, Reflective Liquid Crystal Displays, New York: Wiley (2001) S. K. Hong, G. L. Lim, H. Kikuchi, "Thickness Dependence of Blue Phase Transition Behavior of Chiral Nematic Liquid Crystal", Mol. Cryst. Liq. Cryst., 511, 248 (2009). CrossRef S. K. Hong, H. S. Choi, S. Shibayama, H. Higuchi, H. Kikuchi, "Blue Phase Temperature Range at n-Cyanobiphenyl Homologue Chiral Nematic Liquid-Crystal Mixtures", Mol. Cryst. Liq. Cryst., 528, 32 (2010) CrossRef P. Kula, Synthesis and properties of terphenyl and quaterphenyl based chiral diesters; Liquid Crystals, in press. W. Rejmer, K. Czupryński, W. Drzewiński, "An Influence of Nematic Medium on Helical Twisting Power of Chiral Compounds", Mol. Cryst. Liq. Cryst., 547, 33 (2011). CrossRef H. Kaczmarek, P. Gałka, "Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe", The Open Process Chemistry Journal, 1, 8 (2008). CrossRef

Low Voltage and High Transmittance Polymer-Stabilized Blue-Phase Liquid Crystal Device by Combined In-Plane and Oblique Electric Field along the Horizontal Direction

We propose a polymer-stabilized blue-phase liquid crystal (PS-BPLC) device with high transmittance and low driving voltage by designing the electrode structure. The electrodes are comprised with two interdigitated bottom pixel electrodes with opposite polarities and a top common electrode with 0 V, which is placed in the middle of the two bottom electrodes. Since these electrode structures could generate a strong horizontal electric field and induce a high Kerr effect, we could realize a lower driving voltage (30 V) and higher transmittance characteristics (20%) than those of conventional PS-BPLC cells with an in-plane switching electrode structure.

Fast-Response Blue-Phase Liquid Crystal for Color-Sequential Projection Displays

Color sequential projection display using a vertical field switching (VFS) polymer-stabilized blue phase liquid crystal (BPLC) is proposed. The VFS-BPLC exhibits submillisecond response time which is useful for suppressing color breakup. The proposed projector also has a small throw ratio. With phase compensation, the distortion from oblique LC panel could be corrected.

10.2: Dynamic Decay Processes of a Polymer‐Stabilized Blue‐Phase Liquid Crystal

AbstractFast response time is the most attractive feature of polymer‐stabilized blue phase liquid crystals (PS‐BPLCs). We have investigated the response time of a PS‐BPLC under various electric fields and proposed a double‐relaxation model to explain the possible mechanisms. These results will guide the future device design for keeping fast response time while suppressing hysteresis.

67.4: Submillisecond‐response Blue‐phase Liquid Crystal for Color Sequential Projection Displays

AbstractColor sequential transmissive and reflective projection displays using a vertical field switching (VFS) polymer‐stabilized blue phase liquid crystal (BPLC) are proposed. The VFS‐BPLC exhibits submillisecond response time which is useful for suppressing color breakup, hysteresis‐free for accurate grayscale control, high optical efficiency, and low operation voltage.

16.3: Polarization‐independent and Fast‐response Blue Phase Liquid Crystal Lens with a PEDOT: PSS Film

AbstractA new polarization‐independent and fast‐response adaptive microlens using a polymer‐stabilized blue phase liquid crystal is proposed. The top electrode is coated with a transparent and conductive PEDOT:PSS film to generate linearly varying electric potential from center to edge, while the bottom ITO electrode has a constant potential. Such an adaptive lens is useful for switchable 2D/3D displays.

Polarization independent blue-phase liquid crystal cylindrical lens with a resistive film

We propose a new electrode design for polarization-independent cylindrical lens using a polymer-stabilized blue phase liquid crystal (BPLC). The top electrode is coated with a transparent and resistive film to generate linearly varying electric potential from center to edge; while the bottom iridium tin oxide electrode has a constant potential. Therefore, the vertical electric field across the BPLC layer varies linearly over the lens aperture and a desired parabolic phase profile is obtained automatically according to the Kerr effect. Simulation results show that this simple device is polarization independent and it has parabolic-like phase profile in a large tuning range.

Effects of 1,3,4-oxadiazoles with different rigid cores on the thermal and electro-optical performances of liquid crystalline blue phases

A series of symmetrically 2,5-disubstituted 1,3,4-oxadiazoles with different rigid cores were synthesised under the microwave irradiation based on green chemistry and atom economy. The induced blue phase (BP) behaviours of these bent-shaped compounds were investigated after blending them with a high twisted power chiral dopant or doping them into the chiral nematic liquid crystal (N*LC). It was found that the BP ranges varied greatly with the difference in the rigid cores of 2,5-disubstituted 1,3,4-oxadiazoles, and the bent-shaped molecules with higher miscibility and twisted molecular conformation significantly contribute to the stabilisation of BPs. In addition, the electro-optical performances of pure BPs and polymer-stabilised BPs in the systems containing 1,3,4-oxadiazoles with different rigid cores were also explored, which shows that the Kerr constant decreases after being polymerised and varies with the doping of the compounds possessing different rigid cores in the polymerised mixtures.

Dynamic response of a polymer-stabilized blue-phase liquid crystal

Fast response time is the most attractive feature of polymer-stabilized blue phase liquid crystals (PS-BPLCs). We have investigated the dynamic response of a PS-BPLC under various electric fields and found that the response time becomes slower as the applied electric field exceeds a critical field. Further analyses of experimental data reveal that two relaxation processes are involved. Possible mechanism is proposed to explain the behavior of each process. These results provide useful guidelines for achieving fast response time without hysteresis.

Effect of long flexible chain reactive monomers on the operating voltage of optically isotropic blue phase liquid crystals

A reduction in operating voltage and switch-off time of polymer-stabilised blue phase (BP) liquid crystals has been achieved using reactive monomers (RMs) with long flexible alkyl side-chains. In place of a standard RM, two groups of novel RMs with and without alkyl side-chains have been synthesised. Polymer-stabilised BP systems were obtained by polymerising these RMs using UV irradiation, and their electro-optical properties were compared. Analysis of the results has provided molecular guidelines for future synthesis. The new RMs were purified and characterised chemically.