Flexoelectric coefficients enhancement via doping carbon nanotubes in nematic liquid crystal host

Moghadas, F.; Poursamad, J. B.; Sahrai, Mostafa; Emdadi, M.

doi:10.1140/epje/i2019-11864-1

Cited by 10 publications

(7 citation statements)

References 38 publications

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“…However, in situations where local polarization can have an effect, such as the interactions between NTs and liquids, this may be significant. It has already been seen that liquid crystals can have their flexoelectric coefficients enhanced via doping with CNTs [87]. Thus, this polarization could have a large influence on the behaviour water and other liquids or biomolecules inside or in the vicinity of NTs.…”

Section: Discussionmentioning

confidence: 99%

Flexoelectric-like radial polarization of single-walled nanotubes from first-principles

Bennett¹

2021

Electron. Struct.

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Flexoelectricity is the polar response of an insulator to strain gradients such as bending. While the size dependence makes it weak in bulk systems in comparison to piezoelectricity, it can play a bigger role in nanoscale systems such as thin films and nanotubes (NTs). In this paper we demonstrate using first-principles calculations that the walls of carbon nanotubes (CNTs) and transition metal dichalcogenide nanotubes (TMD NTs) are polarized in the radial direction, the strength of the polarization increasing as the size of the NT decreases. This is reminiscent of a flexoelectric response in bulk insulators, the strain gradient being achieved by bending the 2D monolayers into NTs. For CNTs and TMD NTs with chiral indices (n, m), the radial polarization of the walls P R diverges below C ( n , m ) / a = n 2 + n m + m 2 ∼ 10 , where C(n, m) is the circumference and a is the monolayer lattice constant. For CNTs, P R drops to zero above this value but for TMD NTs there is a non-zero polarization, which is ionic rather than electronic. The size dependence of P R in the TMD NTs is interesting: it increases gradually and reaches a maximum of P R ∼ 100 C cm−2 at C(n, m)/a ∼ 15, then decreases until C(n, m)/a ∼ 10 where it starts to diverge. Measurements of the radial strain on the bonds with respect to the monolayers shows that this polarization is the result of a larger strain on the outer bonds than the inner bonds, but did not explain the peculiar size dependence. These results suggest that while the walls of smaller CNTs and TMD NTs are polarized, the walls of larger TMD NTs are also polarized due to a difference in strain on the inner and outer bonds.

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Section: Discussionmentioning

confidence: 99%

Flexoelectric-like radial polarization of single-walled nanotubes from first-principles

Bennett¹

2021

Electron. Struct.

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“…Their special electrical performance and high aspect ratio of 10~10 3 , like those of liquid crystal, have drawn much attention from researchers in the liquid crystal fields [13][14][15][16]. The effects of the interaction of carbon nanotubes and liquid crystals on their own properties have been studied in several ways for improving the characteristics of both materials.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Chemically Modified Multi-Walled Carbon Nanotubes on the Electro-Optical Properties of a Twisted Nematic Liquid Crystal Display Mode

Gao

Cao

2022

Crystals

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In this study, we have chemically modified multi-walled carbon nanotubes (MWNTs) with different side chains for better dispersion in liquid crystal solutions, and fabricated twisted nematic liquid crystal cells doped with such MWNT derivatives. The introduction of MWNT derivatives affects the alignment of LC molecules with or without external electric fields. Electro-optical property tests showed that the contrast ratio changed slightly with the sharp decrease in drive voltage, improving the drive ability of the twisted nematic liquid crystal display (TN-LCD) mode.

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“…Based on their ordered structure, carbon nanotubes (CNTs) offer many fascinating properties like polarization, high dielectric constant, etc., that could be utilized in various mechanical and electronic devices [11][12][13][14]. During the last two decades, the physical interactions between the LCs and CNTs has obtained an immense research interest worldwide [15][16][17][18][19][20]. The addition of small amount of CNTs into the LCs could lead to some fascinating phenomena.…”

Section: Introductionmentioning

confidence: 99%

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

Singh

Sikarwar

Pandey³

et al. 2021

Electronic Materials

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In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices.

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Flexoelectric coefficients enhancement via doping carbon nanotubes in nematic liquid crystal host

Cited by 10 publications

References 38 publications

Flexoelectric-like radial polarization of single-walled nanotubes from first-principles

Flexoelectric-like radial polarization of single-walled nanotubes from first-principles

The Effect of Chemically Modified Multi-Walled Carbon Nanotubes on the Electro-Optical Properties of a Twisted Nematic Liquid Crystal Display Mode

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

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