Dielectric, electro-optical, and photoluminescence characteristics of ferroelectric liquid crystals on a graphene-coated indium tin oxide substrate

Abstract

Multilayer graphene was deposited on indium tin oxide (ITO) -coated glass plates and characterized by suitable techniques. A liquid crystal sample cell was designed using graphene deposited ITO glass plates without any additional treatment for alignment. Ferroelectric liquid crystal (FLC) material was filled in the sample cell. The effect of multilayer graphene on the characteristics of FLC material was investigated. The extremely high relative permittivity of pristine graphene and charge transfer between graphene and FLC material were consequences of the enormous increase in relative permittivity for the graphene-FLC (GFLC) system as compared to pure FLC. The presence of multilayer graphene suppresses the ionic impurities, comprised in the FLC material at lower frequencies. The ionic charge annihilation mechanism might be responsible for the reduction of ionic impurities. The presence of graphene reduces the net ferroelectricity and results in a change in the spontaneous polarization of pure FLC. Rotational viscosity of the GFLC system also decreases due to the strong π-π interaction between the FLC molecule and multilayer graphene. The photoluminescence of the GFLC system is blueshifted as compared to pure FLC, which is due to the coupling of energy released in the process of charge annihilation and photon emission.

Influence of CdSe quantum dot on molecular/ionic relaxation phenomenon and change in physical parameters of ferroelectric liquid crystal

“…The detailed experimental information regarding dielectric and electro-optical measurements has already been reported in Ref. [11,[18][19][20] and references therein. All the dielectric and E-O measurements have been conducted on planar anchored sample cells.…”

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

“…Table 2 provides a short summary of the reported effects. As can be seen, both decrease [118,119,[121][122][123][124][125][126][127][143][144][145][146][147][148][149][150][151][152] and increase [105,120,[128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][150][151][152][153] in the electrical conductivity of liquid crystals doped with carbon-based nanomaterials were reported.…”

“…The electrical properties of liquid crystals doped with graphene were reported in [121][122][123][124][125][126]. According to [121], graphene sheets, implemented in the design of ferroelectric liquid crystal cell as alignment layers, reduce the electrical conductivity by a factor of ~10.…”

“…According to [121], graphene sheets, implemented in the design of ferroelectric liquid crystal cell as alignment layers, reduce the electrical conductivity by a factor of ~10. This reduction in the conductivity was associated with the charge annihilation process; ionic impurities combine with the surface charge of the graphene, thus annihilating each other [121]. Graphene flakes, mixed with ferroelectric liquid crystal MX40636 (~0.04 wt.…”

Graphene-Based Conducting Metal Oxide Coated D-Shaped Optical Fiber SPR Sensor

“…In addition, graphene also helps in better adsorption of biomolecules due to π −π stacking, thereby improving a systems affinity to such molecules. Also, it has been reported that graphene can be deposited over ITO [17]. These hitherto mentioned ideas motivate us to propose a D-shaped single mode optical fiber sensor.…”