Cell thickness dependence of electrically tunable infrared reflectors based on polymer stabilized cholesteric liquid crystals

Hu, Xiaowen; Haan, Laurens T. de; Khandelwal, Hitesh; Schenning, Albertus P. H. J.; Li, Nian; Zhou, Guofu

doi:10.1007/s40843-017-9163-0

Cited by 13 publications

(10 citation statements)

References 39 publications

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“…[29,30] Electrically responsive CLC devices change color and/or transparency under the influence of an electric field and are favorable for tunable light reflectors or privacy windows in which multiple optical modes can be altered dependent on the users' preferences. [31][32][33][34] Other CLC devices responsive to water, [35,36] chemicals, [37,38] mechanical forces, [39,40] and interfacing biomolecules [41,42] demonstrated dynamic photonic properties and could be used as sensors and lasers, for instance. In particular, "smart" temperature-responsive CLCs [43] have found their way into numerous applications as they can alter their pitch length, and thus their reflective color, autonomously with a change in temperature.…”

Section: Scope Of the Articlementioning

confidence: 99%

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Zhang

Froyen

Schenning

et al. 2021

Advanced Photonics Research

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Cholesteric liquid crystals (CLCs) are a major class of photonic materials that display selective reflection properties arising from their helical ordering. The temperature response of CLCs, comprising dynamic reflection color changes upon variation of temperature, is exploited using material systems consisting of small mesogenic molecules, polymer‐dispersed liquid crystals (PDLCs), polymer‐stabilized liquid crystals (PSLCs), or liquid‐crystalline polymers. Taking advantage of the easy processability and flexibility of the molecular design, these temperature‐responsive CLCs are fabricated into different forms of photonic devices, including cells, coatings, free‐standing films, and 3D objects. Temperature‐responsive devices developed from CLCs are integrated for application in temperature sensors, energy‐saving smart windows, smart labels, actuators, and adding aesthetically pleasing features to common objects. Herein, the device capabilities of the different material systems of temperature‐responsive CLCs are summarized: small mesogenic molecules, PDLCs, PSLCs, and CLC polymers. For each system, examples of different device forms are presented, with their temperature responsiveness and the underlying mechanisms discussed. In addition, the potential of each material system for future device applications and product developments is envisioned.

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Section: Scope Of the Articlementioning

confidence: 99%

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Zhang

Froyen

Schenning

et al. 2021

Advanced Photonics Research

Self Cite

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show abstract

“…As such, the electric field caused a contraction or elongation of the pitch, resulting in band gap shifting and/or broadening. [8,[12][13][14][15][16] A drawback of electrically induced band gap tuning via this method is the usage of an undesired DC electric field, accompanied by transmission losses upon enhancing the amplitude of the electric field due to increased scattering inside the cell. [16,17] Therefore, it would be beneficial if an alternating current (AC) electric field could be used to enact band gap shifting without any loss of optical quality.…”

Section: Introductionmentioning

confidence: 99%

Electrothermal Color Tuning of Cholesteric Liquid Crystals Using Interdigitated Electrode Patterns

Froyen

Wübbenhorst

Liu

et al. 2020

Adv Elect Materials

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A transparent color‐tunable device is presented based on an electrothermal response by using interdigitated electrode patterns. The response is generated by applying an in‐plane AC electric field that heats up a thermosensitive cholesteric liquid crystal mixture. The induced temperature elevations cause band gap shifting (Δλ > 350 nm) up until a colorless state is reached, corresponding to the isotropic phase. Color shifting can be tuned manually by varying the electric field or autonomously by the surrounding temperature. Broadband dielectric spectroscopy reveals that the electrothermal response originates from resistive heating of the transparent electrode pattern in conjunction with the cell capacitance and is therefore largely dependent on the electrode configuration. Hence, the electrothermal response can be easily modified by changing the electrode pattern, frequency and/or voltage, dependent on the user's requirements. Therefore, the ability of this technique to manipulate the autonomous thermal response by an electric field, using only one conductive substrate, shows promise in the field of optoelectronics, sensors, and smart windows.

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“…Due to its unique capability of simultaneously reconstructing the whole information of coherent waves (e.g., amplitude, phase and polarization), holography has become a con-stant innovation source in ultrafast temporal imaging [2,3], optical shaping [4,5], particle assembly [6,7], threedimensional (3D) display [8,9], colored 3D image storage [10][11][12][13][14][15][16], and holographic polymer electrolyte construction [17]. On the other hand, polymer/liquid-crystal (LC) composites have attracted considerable attention due to their unique electro-optic response capability [18][19][20][21]. Integrating holography and polymer/LC composites results in the generation of holographic polymer/LC composites, which not only allows for the reconstruction of holographic images but also provides attractive electrooptic response [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Effect of ketyl radical on the structure and performance of holographic polymer/liquid-crystal composites

et al. 2019

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Holographic polymer/liquid-crystal composites, which are periodically ordered materials with alternative polymer-rich and liquid-crystal-rich phases, have drawn increasing interest due to their unique capabilities of reconstructing colored three-dimensional (3D) images and enabling the electro-optic response. They are formed via photopolymerization induced phase separation upon exposure to laser interference patterns, where a fast photopolymerization is required to facilitate the holographic patterning. Yet, the fast photopolymerization generally leads to depressed phase separation and it remains challenging to boost the holographic performance via kinetics control. Herein, we disclose that the ketyl radical inhibition is able to significantly boost the phase separation and holographic performance by preventing the proliferated diffusion of initiating radicals from the constructive to the destructive regions. Dramatically depressed phase separation is caused when converting the inhibiting ketyl radical to a new initiating radical, indicating the significance of ketyl radical inhibition when designing high performance holographic polymer composites.Scheme 1 Schematic illustration on the conversion of the ketyl radical with an inhibition function to a new initiating radical and the corresponding ordered structures.Scheme 5 Proposed radical diffusion during holographic photopolymerization.

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Cell thickness dependence of electrically tunable infrared reflectors based on polymer stabilized cholesteric liquid crystals

Cited by 13 publications

References 39 publications

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Electrothermal Color Tuning of Cholesteric Liquid Crystals Using Interdigitated Electrode Patterns

Effect of ketyl radical on the structure and performance of holographic polymer/liquid-crystal composites

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