Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Kravchuk, R.; Yaroshchuk, O.; Koval’chuk, A. V.; Karageorgiev, Peter; Stiller, Burkhard; Stumpe, Joachim

doi:10.1117/12.486657

Cited by 2 publications

(3 citation statements)

References 6 publications

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“…As can be seen, in case of non-irradiated cells s(t) curve monotonously decreases. The same behavior of s(t) curve was earlier observed for the case when t iÀf ¼ 1 h [5]. It can be explained with the ion adsorption from LC bulk onto the cell substrates.…”

Section: 1 Lc Filling In Atmospheresupporting

confidence: 80%

“…In contrast to [5], where substrates were irradiated before sample assembling, in present experiments the glued cells were irradiated. The sample preparation procedure was modified to shorter time period between irradiation and LC filling.…”

Section: Samplesmentioning

confidence: 99%

“…First results devoted to this problem we published in [5]. The objects of our studies were LC cells based on ITO and PVCN photoaligning layers.…”

Section: Introductionmentioning

confidence: 99%

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Filling initiated ion transport processesin liquid crystal cell

Kravchuk

Kovalchuk

Yaroshchuk

2002

Molecular Crystals and Liquid Crystals

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The ion adsorption=desorption processes initiated by LC filling in liquid crystal (LC) cells are studied. The LC we used was 5CB and the aligning substrates were UV irradiated polyvinylcinnamate (PVCN) films providing planar alignment of LC. It is shown that intensity of adsorption=desorption processes is strongly determined by purity of LC and irradiation associated parameters, such as exposure dose t exp and time period between irradiation and LC filling t fÀi . To fill the cells we used both 5CB kept in air and 5CB vacuumed at 10 À2 Torr over 1 h. The ion concentration in first portion of LC was estimated to be higher by factor 2 compared with the second one. The cell filling with LC kept in atmosphere is associated with intensive ion adsorption from LC bulk to aligning substrates (when exposure time is zero or when t fÀI > 1h) or with both adsorption and desorption of ions (in case when t fÀi ( 1h). In contrast, cell filling with vacuumed LC mainly initiates ions desorption from the polymer substrates. The latter effect is observed for non-irradiated cells too. This shows that even non-irradiated substrate charges, more likely by adsorption of air ions. The following UV irradiation just increases charging of aligning substrates.

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Section: 1 Lc Filling In Atmospheresupporting

confidence: 80%

Section: Samplesmentioning

confidence: 99%

See 1 more Smart Citation

Filling initiated ion transport processesin liquid crystal cell

Kravchuk

Kovalchuk

Yaroshchuk

2002

Molecular Crystals and Liquid Crystals

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The Interfacial Dipole-to-Dipole Interaction as a Factor of Polar Anchoring in the Cells with Planar Liquid Crystal Alignment

Yaroshchuk

Kovalchuk

Kravchuk

2005

Molecular Crystals and Liquid Crystals

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The frequency of dipole relaxation of liquid crystal (LC) layer at LC-solid interface, f r , is shown to be in full correlation with the polar anchoring energy W p ; the increase of W p is accompanied with the decrease of f r . This correlation is established by the use of the aligning polyimide layers treated with different methods. The anchoring energy increases and the relaxation frequency decreases in the following sequence of processes: rubbing-photoalignment-plasma beam alignment. The correlation between W p and f r is an evidence of strong contribution of dipole-to-dipole interaction at the LC-substrate interface to polar anchoring of LC. Based on this correlation new method of polar anchoring measurement can be developed.

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Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers

Cited by 2 publications

References 6 publications

Filling initiated ion transport processesin liquid crystal cell

Filling initiated ion transport processesin liquid crystal cell

The Interfacial Dipole-to-Dipole Interaction as a Factor of Polar Anchoring in the Cells with Planar Liquid Crystal Alignment

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