Reduction of the Threshold Voltages of Nematic Liquid Crystal Electrooptical Devices by Doping Inorganic Nanoparticles

Abstract

We report the reduction of threshold voltage, V th , of twisted nematic liquid crystal devices by doping the nanoparticles of MgO and SiO 2 . The results are well explained by inserting the experimentally determined values of elastic constants and dielectric anisotropy in the formula, where both of these quantities decrease due to the existence of these nanoparticles. The V th decrease approximately as ffiffi ffi S p , where S being the order parameter. The S is also shown to decrease by doping nanoparticles.

Dielectric and Electro-Optical Properties of Ceramic Nanoparticles Doped Liquid Crystals

“…Fumiaki Haraguchi et al reported the reduction of threshold voltage of twisted nematic LC devices by doping the nanoparticles of MgO and SiO 2 [37]. The results were explained by inserting the experimentally determined values of elastic constants (k eff ) and dielectric anisotropy (Δε) in the formula Where elastic constant (k eff ) is directly proportional to the square of order parameter and dielectric anisotropy (Δε) is directly proportional to the order parameter.…”

“…Instead of synthesizing a large number of high quality LC compound, doping particles into LCs is a potentially cost effective way to attain these important feachures. The doping of nano particles into liquid crystal has emerged as a fascinating area of research to the application point of view [7][8][9][10]. Liquid crystal dispersions containing various types of nano particles have been developed in the recent years [11,12].…”

“…The interaction between nanomaterials and LCs depends upon the various factors like nature of dispersing materials, refractive index of nanomaterials and LCs, shape and size of nanomaterials, concentration of nanomaterials into LC host, density, physical and chemical properties and applied electric field parameters [23][24][25]. Dispersion of nanoparticle in LCs has shown considerable improvement in the existing properties of LC material, exhibiting many special characteristics such as frequency modulation, enhancement of the dielectric anisotropy and birefringence, reduced threshold voltage and induced vertical alignment [26][27][28][29][30][31][32]. Recently, the modifications of the physical properties of liquid crystals by doping nanoparticles have received much attention for the enhancement of the performance of LC electro-optical devices.…”

Permittivity dispersion features of a nematic liquid crystal with quantum dots

“…Допирование наночастицами Si 3 N 4 , ZnO, TiO 2 диаметром 25-35 нм понижало пороговое напряжение по сравнению с чистым ЖК, что объясняли захватом примеси ионов наночастицами за счет кулоновских сил [18]. Понижение порогового напряже-ния при добавлении наночастиц MgO и SiO 2 в твист-ячейках объясняли уменьшением упругих констант и диэлектрической анизотропии [19]. Таким образом, диэлектрические и упругие свойства легированного НЖК зависят от материала, структуры и концентрации наночастиц, а также их взаимодействия с молеку-лами и ионами примеси.…”

Structural Phase Transition in Liquid Crystal Doped with Gold Nanoparticles

“…The properties of such materials, in most cases, significantly differ from those of the host materials. In the past few years there has been a significant increase in the number of published articles dealing with use of metallic, semiconducting, ferromagnetic or ferroelectric nanoparticles, fullerenes and carbon nanotubes in mixture with liquid crystals [1][2][3][4]. Depending on experimental parameters such as nanoparticle functionalization and concentration, size and core material, cell surface treatment, as well as applied electric or magnetic field diverse effects arise in different nematic liquid crystal hosts [4,5].…”