Kinetic analysis of image sticking with adsorption and desorption of ions to a surface of an alignment layer

Mizusaki, Masanobu; Miyashita, Tetsuya; Uchida, Tatsuo

doi:10.1063/1.4747920

Cited by 33 publications

(12 citation statements)

References 21 publications

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“…V r,s is clearly shown to be linearly proportional to V a ; this is because more ions are adsorbed to the interface under a higher voltage. 24,34 Hence, our experimental results prove again that absorbed ion density is proportional to the intensity of electric field in a FFS cell, which validates our assumption in the model and shows same trend as a homogeneous cell. Note that V r,s directly determines the severity of image sticking, so it is crucial to reduce V r,s by optimizing the LC and alignment material properties.…”

Section: Voltage Effectsupporting

confidence: 85%

Image sticking in liquid crystal displays with lateral electric fields

Peng

Chen

et al. 2014

Journal of Applied Physics

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We propose a kinetic model to account for the nonuniform adsorption and desorption processes in fringe field switching (FFS) and in-plane-switching liquid crystal displays. An equation is proposed to describe the generation mechanism of residual DC voltage and good agreements with experiment are obtained. Based on this model, the mechanisms underlying the formation and relaxation processes of residual DC voltage as well as their dependences on offset DC voltage and temperature are investigated. Moreover, the residual DC voltages of FFS cells employing positive and negative dielectric anisotropy LCs are compared and the physics responsible for the observed difference is explained.

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Section: Voltage Effectsupporting

confidence: 85%

Image sticking in liquid crystal displays with lateral electric fields

Peng

Chen

et al. 2014

Journal of Applied Physics

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“…It is known that the VHR is reduced by ionic charges and impurities (including radicals) present in the LC material/layer. Moreover, these ionic charges and/or radicals in the LC layer can be absorbed (or accumulated) on the AL surface under repetitive application of an external DC offset voltage, which leads to the generation of an RDC [28][29][30]. Thus, the VHR is related to the RDC; in general, the VHR tends to decrease with an increasing RDC [30,31].…”

Section: Properties Of Lc Cell: Vhr and Rdcmentioning

confidence: 99%

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

et al. 2021

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This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents. After forming a thin film by mixing trifunctional epoxide [4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline] with the 6FDA−ODA-based PAA, it was confirmed that thermal curing at −110 °C caused an epoxy ring opening reaction, which could result in the formation of a networked polyimide not soluble in tetrahydrofuran. The crosslinked PI film showed a higher rigidity than the neat PI films, as measured by the elastic modulus. Furthermore, based on a dynamic mechanical analysis of the neat PI and crosslinked PI films, the glass transition temperatures (Tgs) were 217 and 339 °C, respectively, which provided further evidence of the formation of crosslinking by the addition of the epoxy reagent. After mechanical rubbing using these two PI films, an LC cell was fabricated using an anisotropic PI film as an LC alignment film. LC cells with crosslinked PI layers showed a high voltage holding ratio and low residual direct current voltage. This suggests that the crosslinked PI has good potential for use as an LC alignment layer material in advanced LCD technologies that require high performance and reliability.

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“…Liquid crystals (LC) are widely used in electro-optic devices because of their unique electro-optic anisotropy; however, the mobile ions in LC cause a lot of problems relating to LC switching. The moving of mobile ions driven by electric forces towards alignment layers results in their accumulation on alignment layers, which finally generates residual direct current (DC) voltage (V rdc ) inside LC cells and adversely affects LC' switching [1][2][3][4][5][6]. During the last several decades, a series of researches focused on distinguishing, detecting mobiles ions, and revealing the influences of mobile ions shifting on LC switching were conducted, and nowadays a lot of explorations are carried out to reduce mobile ions' adverse functions on LC [7][8][9][10][11][12] A lot of attempts have been adopted to prevent the influences of mobile ions on LC electro-optical performances, such as designing special LC molecules, purifying LC, doping LC [13,14], replacing the polyimide (PI) alignment layers with conductive materials [15][16][17][18], and photo-aligning LC [19][20][21], etc.…”

Section: Introductionmentioning

confidence: 99%

Decreasing the Residual DC Voltage by Neutralizing the Charged Mobile Ions in Liquid Crystals

et al. 2019

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The decrease of the residual direct current (DC) voltage (Vrdc) of the anti-parallel liquid crystal (LC) cell using silver (Ag)-doped Polyimide (Ag-d-PI) alignment layers is presented in this manuscript. A series of Ag/PI composite thin layers are prepared by spurting or doping PI thin layers with Ag nano-particles, and Ag/PI composite thin layers are highly transparent and resistive. LC are homogeneously aligned between 2.0 mg/ml Ag-d-PI alignment layers, and the Vrdc of the cell that assembled with Ag-d-PI alignment layers decreases about 82%. The decrease of Vrdc is attributed to the trapping and neutralizing of mobile ions by Ag nano-particles. Regardless of the effect of Ag nano-particles on the conductivity of Ag-d-PI alignment layers, the voltage holding ratio (VHR) of the cells is maintained surprisingly. The experiment results reveal a simple design for a low Vrdc LC cell.

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Kinetic analysis of image sticking with adsorption and desorption of ions to a surface of an alignment layer

Cited by 33 publications

References 21 publications

Image sticking in liquid crystal displays with lateral electric fields

Image sticking in liquid crystal displays with lateral electric fields

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

Decreasing the Residual DC Voltage by Neutralizing the Charged Mobile Ions in Liquid Crystals

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