Fabrication of vertical alignment liquid crystal cell without forming a conventional polyimide-alignment layer

Mizusaki, Masanobu

doi:10.1080/02678292.2018.1542746

Cited by 10 publications

(3 citation statements)

References 15 publications

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“…As it is known, photoalignment is an important and attractive noncontact LC alignment method due to photo-patternable characteristics − and a clean and simple process. Recently, polyimide-free homeotropic or homogeneous photoalignment systems have been realized using photopolymerizable monomers or mixed monomers upon suitable light irradiation. − Photopolymerization of monomers upon linearly polarized light irradiation results in uniform homogeneous alignment of LCs. The resulting alignment is quite stable with improved electro-optical properties.…”

Section: Introductionmentioning

confidence: 99%

Highly Stable, Pretilted Homeotropic Alignment of Liquid Crystals Enabled by In Situ Self-Assembled, Dual-Wavelength Photoalignment

Kumar

Jiang

et al. 2020

ACS Appl. Electron. Mater.

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Homeotropic alignment of liquid crystals (LCs) is one of the key modes used in commercial liquid crystal displays (LCDs) due to its advantages, such as high contrast ratios and fast response speed. Here, we report stable homeotropic LC alignment with a small pretilt angle in a nematic, negative LC host doped with additives including self-aligning agents, photoresponsive azo dyes and reactive mesogen via an in-situ self-assembled, dual-wavelength photoalignment approach. The underlying mechanism of stable, pretilted homeotropic LC alignment was further analyzed in detail. The achieved pretitled homeotropic LC cells are very stable against heat and UV light exposure and demonstrate excellent electro-optical characteristics. The experimental results show that such a noncontact, simple homeotropic alignment technique has big potential in many applications, such as high-quality LCDs, spatial light modulators, and other optoelectronic devices.

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Section: Introductionmentioning

confidence: 99%

Highly Stable, Pretilted Homeotropic Alignment of Liquid Crystals Enabled by In Situ Self-Assembled, Dual-Wavelength Photoalignment

Kumar

Jiang

et al. 2020

ACS Appl. Electron. Mater.

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“…Considering magnificent performance mechanically, durability to higher-temperature, lower absorption to moisture, superior radiation in addition to higher chemical corrosion resistance and better adhesive to the substrates (inorganic materials) (1)(2)(3)(4)(5), polyimides (PIs) are extensively applied as 'liquid crystal' (LC) alignment layer in 'liquid crystal displays' (LCDs) (6). In recent reports, authors mentioned that the Si-based semiconductor devices has been overtaken globally by the LCD device market (7)(8)(9).…”

Section: Introductionmentioning

confidence: 99%

Thickness Dependent Electro-Optical Behaviour of Homeotropically Aligned Nematic Liquid Crystal

Dogra¹,

Sharma²,

Gahrotra³

et al. 2022

ECS Trans.

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The homeotropically aligned liquid crystal (LC) display devices are of great interest in recent time. Thus, in the present work, the thickness dependent electro-optical behaviour of nematic liquid crystal (NLC) in homeotropic alignment (HA) has been studied. To achieve the HA of NLC, polyimide (PI) coated ITO glass substrates were used. Consequently, cleaned ITO glass substrates (with thickness of 0.7 mm) were used for the fabrication of the LC cells. The pure NLC material (LC-BYVA) was filled into PI coated cells by the capillary injection method. Subsequently, the filled cells were examined with the help of polarized optical microscope (POM), which show the good dark and bright orthoscopic textures of NLC in field ON and OFF states, respectively under cross-polarizers. The conoscopic study of the images also confirmed the perfect HA of NLC molecules. The dark states change to good bright state with the change in orientation of NLC director from homeotropic to planar at operating voltages as seen under cross-polarizers. The electro-optical (E-O) study also shows the good contrast ratio (CR) of display cells.

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“…The cholesteric liquid crystal (CLC) materials are used for progressive light shutter applications, which attained the change of transmittance of light passing through the light shutter with the application of an external electric field (1). The CLC light shutter exhibits two optical states; one transparent and the other opaque state and can be directly switched on applying low and high frequency electric fields (2).…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependent Morphological and Electro-Optical Characteristics of Dye Doped Cholesteric Liquid Crystal

et al. 2022

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Cholesteric liquid crystals (CLCs) have gain remarkable attention due to its property of stabilizing the planar (P) and focal conic (FC) states. This paper presents the temperature dependent behavior of cholesteric liquid crystal (CLC) mixed with appropriate amount of dye. The pitch of sample corresponds to visible region (~1 µm) was adjusted by adding appropriate concentration of chiral dopant. The phase transition and morphological behavior was recorded using polarized optical microscope (POM) from planar state to isotropic state by heating the sample using temperature-controller. Experimental results indicated that increase in temperature impacts the morphology of CLC and strongly affects its electro-optical (E-O) properties. Further, POM studies showed that at room temperature dye doped CLC cell has initial transparent state (planar texture) however, when driving voltage was high (~27V) with lower frequency of 1 kHz, P state switched to FC state. On further increasing the temperature, minor distortion was observed in P state in comparison to P state of dye doped CLC cell at room temperature, however, at higher (~ 45˚C) temperature, low driving voltage was required to achieve the stable FC state. Further, FC state was switched to stable P state on applying high frequency (50 kHz) voltage. Afterward, above 45˚C temperature, the textures showed the sustained FC state of dye doped CLC cell with no switching to P state on applying high frequency (50 kHz) voltage. Thus, temperature dependent dye doped CLC cell showed the bi-stability feature upto 45˚C temperature, however, above this temperature showed the fixed FC state.

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Fabrication of vertical alignment liquid crystal cell without forming a conventional polyimide-alignment layer

Cited by 10 publications

References 15 publications

Highly Stable, Pretilted Homeotropic Alignment of Liquid Crystals Enabled by In Situ Self-Assembled, Dual-Wavelength Photoalignment

Highly Stable, Pretilted Homeotropic Alignment of Liquid Crystals Enabled by In Situ Self-Assembled, Dual-Wavelength Photoalignment

Thickness Dependent Electro-Optical Behaviour of Homeotropically Aligned Nematic Liquid Crystal

Temperature Dependent Morphological and Electro-Optical Characteristics of Dye Doped Cholesteric Liquid Crystal

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