Electrooptical Properties of Carbon-Nanotube-Doped Twisted Nematic Liquid Crystal Cell

Abstract

We investigated the electrooptical properties of a carbon nanotube (CNT)-doped twisted nematic (TN) liquid crystal (LC) cell. Experimental results reveal that the doped CNTs influence the elastic constant of LC–CNT dispersion. Using a small amount of CNT dopant, the field-on response time of the LC cell is nearly invariant; the threshold voltage of the cell increases due to the increase in the elastic constant of LC–CNT dispersion. At a higher CNT concentration, the marked increase in the dielectric anisotropy of LC–CNT dispersion markedly decreases the field-on response time and threshold voltage of the LC cell. The field-off response time of this cell decreases with increasing CNT concentration due to the increase in elastic constant and the slight increase in viscosity of LC–CNT dispersion. The field-on and field-off response times of the LC cell are reduced simultaneously when the LC host is doped with a moderate amount of CNT dopant.

On the effect of carbon nanotubes on properties of liquid crystals

“…The situation is however confused by data showing the opposite behaviour: unaffected or even clearly increased switching threshold [25,26,[28][29][30][31], clear signs of increased ion content [26,31] and slower switching [25,26,28]. While it is difficult to understand the origin of the discrepancy between the different reported results, due to lack of information on CNT quality, preparation procedure or crucial aspects of the experimental conditions, there are indications that the CNT concentration plays an important role [26] but also dispersion quality.…”

Carbon Nanotubes in Liquid Crystals

“…a display. Reported effects include reduced effective ion content 16,18,20,21 , increased dielectric anisotropy 16,17,19 , suppressed backflow effects 16,17 , faster 10 electrooptic response due to reduced rotational viscosity 14 and lower switching threshold 16,17,19 . The CNT concentration was in all these works kept extremely low, yet substantial effects were reported.…”

Effects of Nanoscaled Tin-Doped Indium Oxide on Liquid Crystals against Electrostatic Discharge

“…To obtain a higher display quality, the effects of fine particles added in LCs on the characteristics of the LCs have been investigated by several groups [1][2][3][4][5]. The chosen materials range from conducting materials [1,2] to insulating carbon nanotubes (CNTs) [3,4] and ferroelectric particles [5].…”

“…So far the subjects have included various kinds of materials such as metallic Ag-or Pd-nanoparticles [1,2], CNTs [3,4,[11][12][13], diamond particles [14], semiconductive nanotubes [15], cage-like polymeric molecules such as polyhedral oligomeric silsesquioxanes (POSS) [16,17], and ferroelectric particles [5,18]. By using these nanoparticle candidates, newly found texture, switching behavior, or enhanced electro-optical response for the modified LC can be achieved.…”