Thresholdless antiferroelectricity in liquid crystals and its application to displays

Inui, Shiroh; Iimura, Noriko; Suzuki, Tsuyoshi; Iwane, Hiroshi; Miyachi, Kouichi; Takanishi, Yoichi; Fukuda, Atsuo

doi:10.1039/jm9960600671

Cited by 208 publications

(84 citation statements)

References 8 publications

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“…4 Meanwhile, an application of the electric field also induces a sort of phase ͑or more appropriately here called a state͒ transition in the same manner as the thermal energy does to the structure. [5][6][7] This is because the electrical coupling aligns the polarization vectors in the chiral smectic liquid crystals. Hence the state of the liquid crystals transforms from a less-polar to a morepolar state by applying the electric field.…”

Section: Introductionmentioning

confidence: 99%

The effect of confinement on the stability of field induced states and on supercooling in antiferro-ferroelectric phase transitions in chiral smectic liquid crystals

Song

Vij

2009

Journal of Applied Physics

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We investigate both the supercooling and the hysteresis phenomena of the phase transitions between the smectic C * and the smectic C A * phases driven by temperature and electric field, respectively. These two phenomena show similar characteristics for the dependence of transmittance on both the cell thickness and the applied field. The mechanisms for large supercooling and large hysteresis in thin cells are shown to correspond to the suppression of the propagation of solitary wave by the surfaces. Furthermore, these two phenomena are shown to be controlled by a moderate ac field applied across the cell. We present a clear evidence for the existence of at least two field induced subphases ͑called states here͒ between the antiferroelectric and the ferroelectric phases. These are found to correspond to the field induced three-layered and four-layered structures through a comparison of experimental results on the tilt angle and its simulation as well as by discrete changes in the texture by increasing the electric field. The correspondence between the thermotropic phases and the field induced states is demonstrated through measurements of the supercooling/superheating and of the hysteresis as a function of the cell thickness. The instability in the field induced states depends strongly on the cell thickness, and the various states are not observed in a cell of 1.6 µm thickness.

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Section: Introductionmentioning

confidence: 99%

The effect of confinement on the stability of field induced states and on supercooling in antiferro-ferroelectric phase transitions in chiral smectic liquid crystals

Song

Vij

2009

Journal of Applied Physics

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“…[9][10][11] Many groups have explained this electrooptic response using different models. [1][2][3][4][5][6][7][8] Using a detailed experimental study on some FLC mixtures with compensated helix, we have shown 12,13 that the electrostatic model [3][4][5] explains the electro-optic switching characteristics of VFLCs ͑V-shaped FLCs͒ extremely well, and that not only the high spontaneous polarization P S but also the thickness of alignment layer play an important role in obtaining a good V-shaped switching. The electrostatic model stiffens the directors such that, on the average, the tilt plane containing the layer normal is normal to the plane of substrates and P S while in the smectic layer plane is directed along the substrate.…”

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confidence: 99%

“…[1][2][3][4][5][6][7][8] V-shaped switching in surface stabilized ferroelectric liquid crystals ͑FLCs͒ is an attractive electro-optic effect for display applications. [9][10][11] Many groups have explained this electrooptic response using different models.…”

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confidence: 99%

V-shaped electro-optic response observed in a chiral ferroelectric smectic liquid crystal

Manjuladevi

Panarin

Song

et al. 2008

Applied Physics Letters

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We report on the observation of V-shaped switching in a ferroelectric liquid crystal cell over a wide range of temperatures. Results of the optical transmittance in the visible region give us the helical pitch for various temperatures of the ferroelectric liquid crystalline compound used. We show that the helical pitch, in addition to the spontaneous polarization ͑P S ͒ and thickness of the alignment layer of the cell, is an important factor in giving V-shaped switching. A longer or helical compensated mixture gives a better V-shaped switching. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2970039͔The origin of V-shaped ͑thresholdless͒ switching observed in ferroelectric smectic C * ͑SmC * ͒ liquid crystals has been a subject of debate for almost a decade. 1-8 V-shaped switching in surface stabilized ferroelectric liquid crystals ͑FLCs͒ is an attractive electro-optic effect for display applications. 9-11 Many groups have explained this electrooptic response using different models. 1-8 Using a detailed experimental study on some FLC mixtures with compensated helix, we have shown 12,13 that the electrostatic model 3-5 explains the electro-optic switching characteristics of VFLCs ͑V-shaped FLCs͒ extremely well, and that not only the high spontaneous polarization P S but also the thickness of alignment layer play an important role in obtaining a good V-shaped switching. The electrostatic model stiffens the directors such that, on the average, the tilt plane containing the layer normal is normal to the plane of substrates and P S while in the smectic layer plane is directed along the substrate. This arises from an increase in the elastic constant and consequently leads to stiffness in the c directors with an increase in P S , as was initially suggested by Okano. 14 This was recognized by Rudquist et al. 3 and later by Clark and co-workers 4,5 for realizing V-shaped switching in FLC cells. Hasegawa et al. 11 also discussed the importance of large P S in obtaining V-shaped switching with a contrast ratio ͑CR͒ greater than 100. Blinov et al. 15 considered V-shaped switching in terms of an electrical equivalent circuit of the cell and derived an equation for the hysteresis inversion frequency using a triangular wave as applied signal and they suggested methods of increasing this frequency. It may be remarked here that although a triangular wave is used in demonstrating this phenomenon, in the real displays, nevertheless, pulse switching is used in the addressing-schemes. The switching speeds of the liquid crystals consequently come into play and the inversion frequency so derived is inapplicable. In fact, Cassio used MGC Y102 mixture and obtained 100 s response time at room temperature by applying a few volts in this cell geometry. 16 In this letter we present an additional characteristic of the V-shaped switching by observing the electro-optic switching behavior of a pure compound exhibiting SmC * phase over a wide range of temperatures; the length of helical pitch is shown to play an important role. The materi...

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“…[1][2][3][4][5][6][7][8] The reason for interest in them lies in their promise of realizing new types of liquid crystal displays ͑LCDs͒. 9 Since the discovery of V-shaped switching, random 1,2 and the collective models 5,6 were proposed to explain its switching mechanism. Many physical properties have been investigated which support one or both these models.…”

mentioning

confidence: 99%

“…[2][3][4]8 We used two polyimides, RN1199 and RN1266 ͑Nissan Chemical Industries, Ltd.͒, as the aligning material. They were spin coated on glass substrates with an ITO coating.…”

mentioning

confidence: 99%

Surface molecular alignment by in-plane anchoring in the cell showing the V-shaped switching

Seomun

Vij

Hayashi

et al. 2001

Applied Physics Letters

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The surface molecular alignment in a sandwich cell showing V-shaped switching has been investigated using a photocontrolling method. The results indicate that the molecules on the rubbed surface are aligned parallel to the rubbing direction as in an open cell with an air-liquid crystal boundary. This alignment is due to strong in-plane anchoring, due to which the small twisted state appears along the cell thickness through intralayer molecular interaction.

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Thresholdless antiferroelectricity in liquid crystals and its application to displays

Cited by 208 publications

References 8 publications

The effect of confinement on the stability of field induced states and on supercooling in antiferro-ferroelectric phase transitions in chiral smectic liquid crystals

The effect of confinement on the stability of field induced states and on supercooling in antiferro-ferroelectric phase transitions in chiral smectic liquid crystals

V-shaped electro-optic response observed in a chiral ferroelectric smectic liquid crystal

Surface molecular alignment by in-plane anchoring in the cell showing the V-shaped switching

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