Liquid crystal composition and liquid crystal 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 N, at least one compound represented by a general formula II, and at least one compound represented by a general formula M. The invention also provides a liquid crystal display device containing the liquid crystal composition. The liquid crystal composition provided by the invention has properly high optical anisotropy, properly high clearing point, high transmittance, large average elastic constant, good low-temperature stability, high response speed and low rotary viscosity. When the liquid crystal composition is applied to an IPS liquid crystal display device, the transmittance of the display device can be effectively improved, so that the display device can have a 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 liquid crystal display device thereof. Background technique [0002] Liquid crystal display (Liquid Crystal Display, LCD) has obtained rapid development because of its small size, light weight, low power consumption and excellent display quality, and is especially widely used in portable electronic information products. With the increase in the size of LCD screens for portable computers, office applications, and video applications, there are still some problems to be solved in order to enable LCD displays to be used for large-screen display and eventually replace cathode ray tubes (Cathode Ray Tube, CRT). Such as improving viewing angle characteristics, increasing response speed, increasing contrast, increasing transmittance, etc. The relatively narrow viewing angle of the LCD means that when viewed away from the direction perpendicular ...

AI Technical Summary

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

[0007] According to the transmittance formula of IPS mode Transmittance (transmittance, T)∝|Δε| / ε ⊥ ("∝" means "inverse proportional" relationship), if you want to increase the transmittance of positive 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, liquid crystal molecules will tilt to the Z-axis direction under the action of the vertical component of the fringe electric field, resulting in changes 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) It can be seen that effective Δn*d will affect T, if it is necessary to improve 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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