Liquid crystal composition and display device thereof

Abstract

The invention provides a liquid crystal composition, which comprises at least one compound represented by a general formula I, at least one compound represented by a general formula II, at least one compound represented by a general formula III, and at least one compound represented by a general formula M. The invention also provides a display device containing the liquid crystal composition. Theliquid crystal composition provided by the invention has high dielectric anisotropy, properly high optical anisotropy, properly high clearing point, high transmittance, high transmittance, good low-temperature stability and large average elastic constant, so that the liquid crystal display device containing the liquid crystal composition has high contrast ratio, less light scattering and good display effect.

Description

technical field [0001] The invention relates to the field of liquid crystal materials, in particular to a liquid crystal composition and a display device thereof. Background technique [0002] Liquid crystal material is a mixture of organic rod-shaped small molecular compounds that have both fluidity of liquid and anisotropy of crystal at a certain temperature. Liquid crystal display devices use the optical anisotropy and dielectric anisotropy of liquid crystal materials to work, and have been widely used at present. The classification of liquid crystal display elements based on the operation mode of liquid crystal molecules is: phase change (phase change, PC), twisted nematic (twisted nematic, TN), supertwisted nematic (supertwisted nematic, STN), dynamic scattering (dynamic scattering, DS ), ferroelectric liquid crystal (FLC), guest-host (GH), electrically controlled birefringence (ECB), optically compensated bend (OCB), coplanar switching (in- plane switching (IPS), ver...

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Problems solved by technology

They all have their own advantages and disadvantages: MVA mode has the characteristics of high contrast and fast response, but it needs a biaxial compensation film and two elliptical polarizers, so the cost is higher; OCB mode is difficult to maintain stable control with AC voltage , the transmittance of R, G, and B monochromatic light is also different. In addition, in the case of no field, the molecules in the liquid crystal cell are arranged in a direction parallel to the substrate. In order to achieve a curved arrangement, it is necessary to Add a voltage to the box for a few seconds to preset, and then maintain this arrangement at a lower voltage, which is inconvenient to use; IPS mode only needs a linear polarizer without a compensation film, but its response speed is too fast Slow, unable to display fast-moving pictures

[0008] According to the transmittance formula of IPS mode Transmittance (transmittance, T)∝|Δε| / ε ⊥ ("∝" means "inverse proportional" relationship, ε ⊥ Indicates the dielectric constant perpendicular to the direction of the molecular axis), if you want to increase the transmittance of the liquid crystal, you can try to reduce the Δε of the liquid crystal medium, but generally the adjustment range of the driving voltage of the same product is limited

In addition, the liquid crystal molecules will tilt to the Z-axis direction under the action of the vertical component of the fringe electric field, resulting in a change in their optical anisotropy Δn, according to the formula (wherein, χ is the angle between the optical axis of the liquid crystal layer and the optical axis of the polarizer, Δn is the optical anisotropy, d is the cell spacing, and λ is the wavelength). The transmittance of positive liquid crystals can also be considered to increase Δn*d, but the retardation design of each product is fixed

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