Light-induced anchoring transition in a 4,4'-disubstituted azobenzene nematic liquid crystal

Komitov, L.; Ichimura, Kunihiro; Strigazzi, Alfredo

doi:10.1080/026782900203209

Cited by 56 publications

(33 citation statements)

References 12 publications

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“…Azobenzene based liquid crystalline material have been frequently discussed for their sensitivity of chromophoric group towards light and found to exhibit interesting optical properties, enable us to study the materials in holography, optical storage device, optical switching and establish widespread applications in display technology [1][2][3][4][5]. By virtue of their fluidity and translational periodicity, liquid crystal molecules are more easily induced into a new arrangement when triggered by an electric field, [6,7] temperature, [8][9][10] and light [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Effect of azo and ester linkages on rod shaped Schiff base liquid crystals and their photophysical investigations

Selvarasu

Kannan

2016

Journal of Molecular Structure

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Section: Introductionmentioning

confidence: 99%

Effect of azo and ester linkages on rod shaped Schiff base liquid crystals and their photophysical investigations

Selvarasu

Kannan

2016

Journal of Molecular Structure

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“…A series of methods have been developed to control the director boundary conditions, for example, irradiating alignment layers with ion beams, 20 doping the LC cells with nanoparticles, 21 or forming polymer structures on a substrate surface via electrostatic force 22,23 or UV light field. [24][25][26] In this present paper, we speculate that the photorefractive space-charge field may control the anchoring of the LC director at the cell substrates, and therefore affect the grating formation. We study the influence of the LC director anchoring energy and the easy axis direction on energy transfer between light beams incident on the hybrid cell.…”

Section: Introductionmentioning

confidence: 99%

Two beam energy exchange in hybrid liquid crystal cells with photorefractive field controlled boundary conditions

et al. 2016

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We develop a theory describing energy gain when two light beams intersect in a hybrid nematic liquid crystal (LC) cell with photorefractive crystalline substrates. A periodic space-charge field induced by interfering light beams in the photorefractive substrates penetrates into the LC layer and reorients the director. We account for two main mechanisms of the LC director reorientation: the interaction of the photorefractive field with the LC flexopolarization and the director easy axis at the cell boundaries. It is shown that the resulting director grating is a sum of two in-phase gratings: the flexoelectric effect driven grating and the boundary-driven grating. Each light beam diffracts from the induced gratings leading to an energy exchange between beams. We evaluate the signal beam gain coefficient and analyze its dependence on the director anchoring energy and the magnitude of the director easy axis modulation.

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“…The azo groups in cis configuration after UV irradiation could be adsorbed on the polar surface due to strong intermolecular interactions such as dipole-dipole interactions, hydrogen bonding, and p-p interactions. [19] For the planar and bare glass cells used here, they had polyimide or hydroxide groups (SiÀOH) on the glass surface, respectively. After UV irradiation, the azo group undergoes a trans-cis isomerization and the exposed nitrogen atom of the bent azo group forms attractive hydrogen bonding with the glass surface ( Figure S11).…”

mentioning

confidence: 99%

Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles

et al. 2015

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Stimuli-directed alignment control of liquid crystals (LCs) with desired molecular orientation is currently in the limelight for the development of smart functional materials and devices. Here, photoresponsive azo thiol (AzoSH) was grafted onto gold nanoparticles (GNPs). The resulting hybrid GNPs were able to homogeneously mix with a commercially available nematic LC host, as evidenced by Cryo-TEM. Interestingly, the LC nanocomposites were found to undergo reversible alignment transition upon light irradiation as a consequence of the trans-cis photoisomerization of the azo groups on the GNP surface. LC molecules in either planar or bare glass cells were able to change their alignment to vertical upon UV irradiation, while the vertically aligned LC molecules returned to the planar or random orientation under visible irradiation. Neither the azo thiol molecules nor the unfunctionalized GNPs alone promoted the alignment of the LC molecules in the system upon light irradiation. The photoinduced vertical alignment without applied electric or magnetic field was very stable over time and with respect to temperature. Furthermore, an optically switchable device based on the photostimulated reversible alignment control of LCs was demonstrated.

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Light-induced anchoring transition in a 4,4'-disubstituted azobenzene nematic liquid crystal

Cited by 56 publications

References 12 publications

Effect of azo and ester linkages on rod shaped Schiff base liquid crystals and their photophysical investigations

Effect of azo and ester linkages on rod shaped Schiff base liquid crystals and their photophysical investigations

Two beam energy exchange in hybrid liquid crystal cells with photorefractive field controlled boundary conditions

Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles

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