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Characteristics of Liquid Crystal Materials for TFT Liquid Crystal Display

Many people know what the characteristics of LCD display TFT are, but do you know what are the characteristics of LCD display TFT material? Today, KINGTECH will tell you about the knowledge of the characteristics of LCD display TFT materials. TFT also adopts the principle of TN type electro-optic effect, but the TFT liquid crystal material is different from the traditional liquid crystal material. In addition to good physical and chemical stability and a wide operating temperature range, TFT display liquid crystal materials must also have the following characteristics:

(1) Low viscosity, the viscosity should be less than 35 mPa 8226/s at 20 °C to meet the needs of fast response.

(2) Low threshold voltage (Vth) to achieve low voltage drive and reduce power consumption.

(3) High voltage holding ratio (V.H.R), that is, LCD materials must have high resistivity, generally at least greater than 1012Ω826cm.

(4) The optical anisotropy (Δn) is matched with the TFT to eliminate the rainbow effect and obtain a larger contrast ratio and a wide-angle field of view. The range of △n value should be between 0.07~0.11.

At present, among the liquid crystal display materials, the TN-liquid crystal display screen has gradually entered a recession period, the market demand is gradually shrinking, the production capacity is excessive, the price competition is fierce, and there is no investment value. STN LCD will gradually enter a mature stage, the market demand will grow steadily, and the production technology will be fully mature. LCD display TFT is entering a new round of rapid growth in the world, the market demand will increase sharply, and it is expected to become one of the most promising display materials in the 21st century.

Although liquid crystal materials whose end groups are cyano groups, such as biphenyl and phenylcyclohexane liquid crystals, have been widely used in TN and STN liquid crystal displays, their viscosity is compared with that of fluorine-containing liquid crystals with the same molecular structure. Still high, these unfavorable factors limit the application of this type of compounds in LCD display TFTs. Ester liquid crystal has the characteristics of simple synthesis method, wide variety, and wide phase transition range, but its high viscosity greatly reduces the dosage in TFT formulation. Therefore, the development of new liquid crystal compounds that meet the above requirements has become the focus of liquid crystal chemistry research.

Liquid crystal materials have developed rapidly with the development of liquid crystal devices, from biphenyl nitrile, esters, oxygen-containing heterocyclic benzenes, and pyrimidine ring liquid crystal compounds to cyclohexyl (bi)benzene, diphenylacetylene, ethyl Bridge bonds and various fluorine-containing aromatic ring liquid crystal compounds have recently been synthesized in Japan with vinylidene fluoride liquid crystal compounds with stable structure. Its molecular structure is more and more stable, and it continuously meets the performance requirements of STN and LCD display TFTs. The market volume of liquid crystal displays in the world is increasing, but the share of the liquid crystal industry is very small, and it is concentrated in TN liquid crystal materials, and there is a certain development in TFT liquid crystal materials. Call on the country to take active measures to strengthen the talent and capital investment in the research and development of liquid crystal display devices and materials, and tilt upstream in the flat panel display industry to revitalize the liquid crystal display industry.

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