Optical switching in guest–host liquid crystal devices driven by photo- and thermal isomerisation of azobenzene

Goda, Kazuya; Omori, Maya; Takatoh, Kohki

doi:10.1080/02678292.2017.1355987

Cited by 36 publications

(6 citation statements)

References 20 publications

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“…Azobenzene dyes are a class of functional materials that can be modified by thermal and photochemical treatment, which could have wide applications in molecular switches, molecular machines, memory storage, and nanodevices. − As known to all, azobenzene dye could undergo a reversible isomerization between cis and trans conformations at appropriate conditions. There are two possible isomerization pathways: via rotation or inversion.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on Photothermal Properties of Azobenzene Sulfonate/Magnesium–Aluminum Hydroxide Composite Dye

Zhang

Zhu

et al. 2023

ACS Omega

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The assembly of various azo dyes and pigments with inorganic layered materials could develop new types of intercalation materials. The electronic structures and photothermal properties of composite materials (AbS–-LDH) constituted by azobenzene sulfonate anions (AbS–) and Mg–Al layered double hydroxide (LDH) lamella were theoretically studied at the M06-2X/def2-TZVP//M06-2X/6-31G(d,p) level using density functional theory and time-dependent density functional theory. Meanwhile, the influences of LDH lamella on the AbS– in AbS–-LDH materials were investigated. The calculated results showed that the addition of LDH lamella could lower the isomerization energy barrier of CAbS– anions (CAbS– stands for cis AbS–). The thermal isomerization mechanisms of AbS–-LDH and AbS were related to the conformational change of the azo group, out-of-plane rotation and in-plane inversion. The LDH lamella could reduce the energy gap of the n → π* and π → π* electronic transition and lead to a red-shift in the absorption spectra. When a polar solvent DMSO was applied, the excitation energy of the AbS–-LDHs was increased, making its photostability stronger than in nonpolar solvent and solvent-free.

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Section: Introductionmentioning

confidence: 99%

Theoretical Study on Photothermal Properties of Azobenzene Sulfonate/Magnesium–Aluminum Hydroxide Composite Dye

Zhang

Zhu

et al. 2023

ACS Omega

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“…[ 39–41 ] Nevertheless, some recent studies have reported the feasible evolution of LC‐based smart windows with passive control, which can achieve truly “smart” functionality by responding to changes in temperature T (thermoresponsive) [ 42,43 ] or light (photoresponsive). [ 44–46 ] It is an effective means to devise a passive‐control LC smart window by incorporating photoisomerizable (e.g., azobenzene), [ 36,47 ] photothermal (e.g., isobutyl‐substituted diimmonium borate), [ 43 ] or photoconductive substances (e.g., zinc phthalocyanine) [ 48 ] that can respond to environmental stimuli. Although adding extra materials into a mesogenic host may offer merits for breakthrough applications in passively stimulated control of smart windows, there exist several potential problems for practical use, including the shortened switching lifetime, [ 43 ] degradation in optical performance, [ 48 ] and long response time.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Active–Passive Control of an Unconventional Smart Window Based on Dye‐Doped Dual‐Frequency Liquid Crystal

Sung,

Lee

2023

Advanced Photonics Research

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The allure of dual‐frequency liquid crystal (DFLC) stems from its unique feature of the switchable and revertible sign of dielectric anisotropy. In addition to the common frequency‐modulation method, this study focuses on manipulating the dielectric anisotropy in DFLC through change in temperature. Herein, the hybrid control of a dichroic‐dye‐doped DFLC smart window is proposed, which offers a passive‐control function by reacting to the temperature and automatically switching to one of the three distinct transmission levels: the transparent, variably gray (tinted or translucent), and opaque states. In contrast to conventional, passively controlled smart windows that typically exhibit a gray or opaque state at high temperatures and become transparent at low temperatures, the suggested smart window thermally operates in the opposite manner, presenting a unique characteristic that holds significant potential for a wide range of applications. This thermally reverse‐mode smart window allows one to actively control the degree of transparency by applied voltage at various frequencies as well. A parameter termed the “crossover temperature” is introduced as an indicator of the potency for the change in dielectric anisotropy of the DFLC by temperature. The operation scheme of the hybrid electrical‐and‐thermal control for the proposed vertically aligned dye‐doped DFLC smart window is summarized.

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“…The advantage of a photo-controllable liquid crystal smart window is that it can automatically adjust transmittance from high to low upon exposure to UV, as in sunlight, and so self-adjust without extra energy input. The photo-controllable liquid crystal smart window requires additional photo-sensitive material (such as photosensitive chiral azobenzene [14,15], photochromic dye [16], or azo dye [17]). Most of the photo-controlled liquid crystal smart windows perform the sole function of either absorption or scattering.…”

Section: Introductionmentioning

confidence: 99%

Smart Window with Active-Passive Hybrid Control

et al. 2020

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Dimming and scattering control are two of the major features of smart windows, which provide adjustable sunlight intensity and protect the privacy of people in a building. A hybrid photo- and electrical-controllable smart window that exploits salt and photochromic dichroic dye-doped cholesteric liquid crystal was developed. The photochromic dichroic dye causes a change in transmittance from high to low upon exposure to sunlight. When the light source is removed, the smart window returns from colored to colorless. The salt-doped cholesteric liquid crystal can be bi-stably switched from transparent into the scattering state by a low-frequency voltage pulse and switched back to its transparent state by a high-frequency voltage pulse. In its operating mode, an LC smart window can be passively dimmed by sunlight and the haze can be actively controlled by applying an electrical field to it; it therefore exhibits four optical states—transparent, scattering, dark clear, and dark opaque. Each state is stable in the absence of an applied voltage. This smart window can automatically dim when the sunlight gets stronger, and according to user needs, actively adjust the haze to achieve privacy protection.

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Optical switching in guest–host liquid crystal devices driven by photo- and thermal isomerisation of azobenzene

Cited by 36 publications

References 20 publications

Theoretical Study on Photothermal Properties of Azobenzene Sulfonate/Magnesium–Aluminum Hydroxide Composite Dye

Theoretical Study on Photothermal Properties of Azobenzene Sulfonate/Magnesium–Aluminum Hydroxide Composite Dye

Hybrid Active–Passive Control of an Unconventional Smart Window Based on Dye‐Doped Dual‐Frequency Liquid Crystal

Smart Window with Active-Passive Hybrid Control

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