Enhancement of electrical conductivity of a liquid crystal-gold nanoparticle composite by a gel network of aerosil particles

Abstract

We report electrical conductivity measurements on a pure nematic liquid crystal (LC) and its composites comprising Gold nanoparticles (GNPs) as well as aerosil particles. The inclusion of aerosil particles creating a gel network, albeit being non-conducting, surprisingly enhances the already high conductivity of the LC-GNP material. The presence of aerosil also makes the frequency dependence of the conductivity compatible with the universal phenomenon expected for disordered solids despite the LC confined in the network is still a liquid. The nature of the aerosil corona (hydrophobic/hydrophilic) also controls the behavior. We argue that these features are caused by the amelioration of the percolation network of GNPs through the primary gel network of the hydrogen bonding aerosil particles. The concept can be generalized for a variety of systems wherein metal nanoparticles are embedded in an insulating matrix.

Anisotropic Fast Electrically Switchable Emission from Composites of CsPbBr3 Perovskite Quantum Cuboids in a Nematic Liquid Crystal

“…Recalling that the efficiency of the LEDs is lower in the green/yellow spectral range, the system investigated here may be attractive. Nano‐soft composites comprising LCs as host and nanostructures as the guest is an emerging area of research that gets benefitted by the unique characters of the latter in the self‐assembling features of LCs . A variety of nanoparticles have been employed to alter/tune the LC properties.…”

Dielectric Spectroscopy Analysis of Liquid Crystals Recovered from End-of-Life Liquid Crystal Displays

“…Equation (8) can also be written in the following form, considering: σ DC where σ DC represents the DC conductivity, f c stands for the characteristic frequency, and n is a parameter, which represents the degree of interaction between the mobile ions and their surroundings. The value of n is normally situated between 0 and 1, however some authors have found values where n > 1 [ 33 , 34 , 35 , 36 ]. Many other models are available to analyze the frequency dependence of the complex conductivity like Cole–Cole, Cole–Davidson, Havriliak–Negami, or Kohlrausch–Williams–Watts functions transformed beforehand into their conductivity representations [ 37 , 38 , 39 , 40 , 41 ].…”

Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

“…This increase in the conductivity is attributed to the formation of chains of gold nanoparticles [162,164]. The high electrical conductivity of nematic liquid crystal-gold nanoparticle nano-composites can be enhanced even more by mixing them with dielectric aerosil particles [165]. The formation of chains and networks of metal nanoparticles in liquid crystal nano-composites points to the involvement of the percolation processes.…”

“…Table 3 provides a short summary of their effects on the electrical properties of liquid crystals [154][155][156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172]. The majority of published papers report an increase in the electrical conductivity of liquid crystals doped with metal nanoparticles [156][157][158][160][161][162][163][164][165][166][167]169,171].…”