Investigation on newly designed low resistivity polyimide-type alignment layer for reducing DC image sticking of in-plane switching liquid crystal display

Lee, Tae Rim; Kim, Jin Ho; Lee, Seung Hee; Jun, Myung Chul; Baik, Hong Koo

doi:10.1080/02678292.2016.1239775

Cited by 19 publications

(12 citation statements)

References 26 publications

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“…Low-resistivity PI-2 obtained low RDC and low VHR characteristics for the LC cells, while high-resistivity PIs provided the LC cells with high VHR and high RDC features. For example, PI-2 exhibited a RDC value of 915 mV, which is comparable or lower than those of the commercial partially imidized PI alignment layers (~4000 mV for JALS-146, Japan Synthetic Rubber, Japan) [21]. Interestingly, PI-3 achieved both of the highest VHR and relatively lower RDC feature simultaneously.…”

Section: Optical and Electro-optical Propertiesmentioning

confidence: 90%

“…RDC could be minimized by adjusting the absorption/desorption of ions in the organic materials in LCDs [20]. It has been well established that the PI alignment layer influences both of the VHR and RDC parameters of the TFT-LCDs [21]. It has been proven that LC cells fabricated with PI alignment layers with high electrical resistivity can usually lead a high VHR feature for the devices [22].…”

mentioning

confidence: 99%

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Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

Zhi¹,

Bi²,

Liu³

et al. 2019

Express Polym. Lett.

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Polyimide (PI) represents a class of high performance heteroaromatic polymers characterized by excellent thermal and environmental stability, high mechanical and dielectric properties as well as flexible molecular structure designability [1-3]. Various functionalities have been achieved for PIs via elaborate combination of specific dianhydride and diamine monomers so as to meet the property demands of high-tech applications [4-6]. Among the various functional PIs, semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines proved to possess the best combined properties considering the polymerization reactivity and the acidity/basicity of the starting monomers [7]. Thus, such kinds of semi-alicyclic PIs usually exhibited superior thermal and mechanical properties, and higher molecular weights to their analogous PIs derived from aromatic dianhydrides and alicyclic diamines or from both of alicyclic dianhydride and diamines [8]. Good comprehensive properties of semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines make them much attractive in optoelectronic fields in recent years [9-11]. The successful 923

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Section: Optical and Electro-optical Propertiesmentioning

confidence: 90%

mentioning

confidence: 99%

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

Zhi¹,

Bi²,

Liu³

et al. 2019

Express Polym. Lett.

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“…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. Compared with other methods, doping is much easier; however, doping LC with nano-materials brings new issues, for instance, the doped nano-materials are too poor to be dispersed, and the aggregation of these nano-materials makes LC insensitively respond to external voltage.…”

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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“…On the other hand, the alignment layer is a key factor influencing image sticking. Previous studies reduced ion adsorption and increased the voltage holding ratio in the alignment layer by changing the structure and composition of the materials [ 31 , 32 ]. Lowering the tilt angle and increasing the thickness of alignment layers could also improve image sticking [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Image Quality in LCD by Doping γ-Fe2O3 Nanoparticles and Reducing Friction Torque Difference

Gao

Dai

et al. 2018

Nanomaterials

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Improving image sticking in liquid crystal display (LCD) has attracted tremendous interest because of its potential to enhance the quality of the display image. Here, we proposed a method to evaluate the residual direct current (DC) voltage by varying liquid crystal (LC) cell capacitance under the combined action of alternating current (AC) and DC signals. This method was then used to study the improvement of image sticking by doping γ-Fe2O3 nanoparticles into LC materials and adjusting the friction torque difference of the upper and lower substrates. Detailed analysis and comparison of residual characteristics for LC materials with different doping concentrations revealed that the LC material, added with 0.02 wt% γ-Fe2O3 nanoparticles, can absorb the majority of free ions stably, thereby reducing the residual DC voltage and extending the time to reach the saturated state. The physical properties of the LC materials were enhanced by the addition of a small amount of nanoparticles and the response time of doping 0.02 wt% γ-Fe2O3 nanoparticles was about 10% faster than that of pure LC. Furthermore, the lower absolute value of the friction torque difference between the upper and lower substrates contributed to the reduction of the residual DC voltage induced by ion adsorption in the LC cell under the same conditions. To promote the image quality of different display frames in the switching process, we added small amounts of the nanoparticles to the LC materials and controlled friction technology accurately to ensure the same torque. Both approaches were proven to be highly feasible.

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Investigation on newly designed low resistivity polyimide-type alignment layer for reducing DC image sticking of in-plane switching liquid crystal display

Cited by 19 publications

References 26 publications

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

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

Enhancement of Image Quality in LCD by Doping γ-Fe2O3 Nanoparticles and Reducing Friction Torque Difference

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