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Ube T, Yoshida M, Kurihara S, Ikeda T. Sunlight-Driven Smart Windows with a Wide Temperature Range of Optical Switching Based on Chiral Nematic Liquid Crystals. ACS APPLIED MATERIALS & INTERFACES 2024; 16:28638-28644. [PMID: 38783829 DOI: 10.1021/acsami.4c04370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Photoresponsive liquid crystals are promising materials for sunlight-driven smart windows, which can automatically change their optical states in response to sunlight and control energy flow between the inside and outside of a building. Herein, liquid-crystalline systems are developed that show a transparent-scattering transition upon irradiation with sunlight in a wide temperature range. Push-pull azobenzenes with axial chirality have been newly developed as photochromic chiral dopants to allow changes in mesostructures of liquid crystals in response to sunlight. To realize optical switching, photochromic and photoinert chiral compounds with opposite handedness of helical twisting are doped in liquid crystals. This liquid crystalline sample with a compensated nematic phase is transparent in its initial state. Upon irradiation with sunlight, this sample transforms to a scattering state due to the formation of helical mesostructures along with photoisomerization of azobenzene moieties and the change in the helical twisting power. After the cease of irradiation, the sample reverts to the transparent state through thermal back isomerization of azobenzene moieties. This system significantly improves the operating temperature range of sunlight-driven smart windows based on liquid crystals: the transparent-scattering transition is observed at 4-42 °C. The present mechanism allows development of autonomous and wireless smart windows adaptable to various environments.
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Affiliation(s)
- Toru Ube
- Research & Development Initiative, Chuo University, Tokyo 112-8551, Japan
| | - Marie Yoshida
- Graduate School of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Seiji Kurihara
- Research & Development Initiative, Chuo University, Tokyo 112-8551, Japan
| | - Tomiki Ikeda
- Research & Development Initiative, Chuo University, Tokyo 112-8551, Japan
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2
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Meng X, Lin S, Chen S, Shen X, Guo D, Guo J. Recent Advances in Smart Windows Based on Photo-Responsive Liquid Crystals Featuring Phase Transition. Chempluschem 2024; 89:e202300700. [PMID: 38230830 DOI: 10.1002/cplu.202300700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/18/2024]
Abstract
A smart window is an optical dimming device with intelligent functions that can control its relevant performances through external stimuli, achieving functions such as privacy protection and temperature regulation. Light is an ideal stimulus for regulating smart windows, which is noninvasive and allows self-adaptable manipulation of materials. This review highlights recent significant achievements in smart windows constructed by photo-responsive liquid crystals (LCs) systems that can undergo the transition between different phases. The smart windows based on photo-responsive LCs are used in a plethora of areas, including privacy protection, absorption glass, building decoration, energy saving, and climate modulation applications. The review concludes with a brief perspective on some significant challenges and opportunities for the future development of photo-responsive smart windows, which is crucial for expanding the applications of smart windows and improving their performances.
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Affiliation(s)
- Xianyu Meng
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Siyang Lin
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Shuo Chen
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Xuanzhe Shen
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Dekang Guo
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Jinbao Guo
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, and College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
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Lin S, Zhang Y, Guo D, Song C, Guo J. Polymer-Stabilized Liquid Crystal Films Containing Dithienyldicyanoethene-Based Chiral Photoswitch: Multi-Modulation for Environment-Adaptative Smart Windows. Chemistry 2023; 29:e202300993. [PMID: 37154210 DOI: 10.1002/chem.202300993] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/07/2023] [Accepted: 05/08/2023] [Indexed: 05/10/2023]
Abstract
A polymer-stabilized liquid crystal (PSLC)-based environment-adaptative smart window with multi-modulations is demonstrated. This PSLC system contains a right-handed dithienyldicyanoethene-based chiral photoswitch and a chiral dopant, S811, with opposite handedness, of which the reversible cis-trans photoisomerization of the switch can drive self-shading of the smart window under UV light stimulus because of the transition from nematic phase to cholesteric one. With the assistance of solar heat, the opacity of the smart window can be deepened because the heat promotes the isomerization conversion rate of the switch. This switch has no thermal relaxation at room temperature, therefore, the smart window exhibits dual stabilization: transparent state (cis-isomer) and opaque state (trans-isomer). Moreover, the incident intensity of sunlight can be regulated by an electric field, which allows the smart window to adapt to some specific situations. Such an energy-saving device can be used in buildings and vehicles to control indoor temperature and adapt to the required ambiance.
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Affiliation(s)
- Siyang Lin
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Yiyu Zhang
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Dekang Guo
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Chunfeng Song
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Jinbao Guo
- Key Laboratory of Carbon Fibers and Functional Polymers, Ministry of Education, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
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Vasanthi T, Balasubramanian V, Balamuralikrishnan S, Vijayakumar VN. Influence of Methylene Blue on Optical and Thermal Properties of Dye-Doped Hydrogen-Bonded Liquid Crystal Mixture. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2022. [DOI: 10.1134/s0036024422130209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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5
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Alamro FS, Ahmed HA, Bedowr NS, Khushaim MS, El-atawy MA. New Advanced Liquid Crystalline Materials Bearing Bis-Azomethine as Central Spacer. Polymers (Basel) 2022; 14:1256. [PMID: 35335586 PMCID: PMC8953589 DOI: 10.3390/polym14061256] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 02/01/2023] Open
Abstract
In this study, a homologous series of novel liquid crystalline compounds bearing the bis-azomethine central linkage (-CH=N-N=CH-), namely ((1E,1'E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(4,1-phenylene) dialkanoate (In), was synthesized, and the mesophase and thermal properties were investigated theoretically and experimentally. The molecular structures of the prepared compounds were determined using elemental analysis, NMR, and FT-IR spectroscopy. The mesophase transitions were detected by differential scanning calorimetry (DSC), and the mesophases were identified using polarized optical microscopy (POM). The results indicated that the derivative with the shortest length (I5) was purely nematogenic, while the other homologues (I9 and I15) possessed SmC mesophases. The optimal geometrical structures of the investigated group were derived theoretically. The estimated results demonstrated that all homologues were mesomorphic, and their type depended on the length of the terminal chains. Computations based on density functional theory (DFT) were used to explain the experimental data. The calculated dipole moment, polarizability, thermal energy, and molecular electrostatic potential all showed that it was possible to predict the mesophase type and stability, which varied according to the size of the molecule.
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Affiliation(s)
- Fowzia S. Alamro
- Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia;
| | - Hoda A. Ahmed
- Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt
- Chemistry Department, College of Sciences, Taibah University, Yanbu 30799, Saudi Arabia;
| | - Noha S. Bedowr
- Chemistry Department, College of Sciences, Taibah University, Yanbu 30799, Saudi Arabia;
| | - Muna S. Khushaim
- Department of Physics, Faculty of Science, Taibah University, P.O. Box 30002, Al-Madina 41447, Saudi Arabia;
- Nanotechonolgy Center, Taibah University, P.O. Box 30002, Al-Madina 41447, Saudi Arabia
| | - Mohamed A. El-atawy
- Chemistry Department, College of Sciences, Taibah University, Yanbu 30799, Saudi Arabia;
- Chemistry Department, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahemia, Alexandria 21321, Egypt
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6
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Yuan Y, Xie J, Ma Y, Luo D, Fan F, Wen S. Low-voltage-driven liquid crystal scattering-controllable device based on defects from rapidly varying boundary. OPTICS LETTERS 2022; 47:957-960. [PMID: 35167568 DOI: 10.1364/ol.450620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
In this work, we disclose a method to fabricate an electronically tunable liquid crystal (LC) device that can switch between scattering and transparent state. The light scattering domain is attributed to defects from a rapidly varying boundary based on planar random photo-alignment. Distinct from the LC/polymer composite or haze-control LC elements based on patterned electrodes or a well-designed mask, there is no requirement for a complicated process or other auxiliary additives, as only positive dielectric nematic LCs are required. The device exhibits low driving voltage, small power consumption, and good ability to hide images, where the transparent state only needs a supply of 10 Vrms to offer 7.8% of haze, while with 1.1 Vrms, the device provides 58.7% of haze. The good performance and simple fabrication process reveal enormous promising applications in energy-conservation building, privacy protection, and transparent display.
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7
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Wang YQ, Wu PC, Lee MJ, Lee W. Photocontrolled capacitive biosensor based on photoresponsive azobenzene-doped liquid crystals for label-free protein assay. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.117908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Farooq S, Ngaini Z. Mesomeric Effects of Azobenzene Bearing Natural Product-Based Molecules for Liquid Crystal Materials: An Overview. Curr Org Synth 2021; 18:318-332. [PMID: 32778031 DOI: 10.2174/1570179417666200810142857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 06/22/2020] [Accepted: 07/02/2020] [Indexed: 11/22/2022]
Abstract
Latest progress in the liquid crystal (LC) field related to azo molecules incorporated into natural product- based moieties for the improvement of LC texture and mesomeric phases has received great interest among researchers. A LC containing natural product-based moieties i.e. menthol, kojic acid, cholesterol and chalcone with stable azo and azobenzene scaffolds with specific optical tunability, has been widely used in photo-active materials such as Liquid Crystal Display (LCD), LC films, smart windows and other devices. This review discusses the influence of azobenzene, a renowned photo-responsive and stable LC scaffold, in mesogenic phases due to photo-isomerization and optical switching. The incorporation of mesomeric phases of natural product moieties to azo molecules has improved the properties of LC, i.e, from the nematic phase to the smectic phase with proper magnetic field alignment. Natural product-based LC can be useful in numerous applications, especially practical electronic or optic devices such as optical image storage, display devices, solar cells, optical switching.
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Affiliation(s)
- Saba Farooq
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
| | - Zainab Ngaini
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
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Liu J, Wang Y, Wang J, Zhou G, Ikeda T, Jiang L. Inkless Rewritable Photonic Crystals Paper Enabled by a Light-Driven Azobenzene Mesogen Switch. ACS APPLIED MATERIALS & INTERFACES 2021; 13:12383-12392. [PMID: 33656314 DOI: 10.1021/acsami.0c22668] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Rewritable paper, as an environment-friendly approach of information transmission, has potential possibility to conserve energy and promote a sustainable development of our society. Recently, photonic crystals (PCs) have become a research hotspot in the development of rewritable paper. However, there are still many shortcomings that limit the further application of PC paper, such as slow response sensitivity, short-cycle lifetime, poor storage stability, and so on. Herein, we constructed an optically rewritable azobenzene inverse opals (AZOIOs) with a thin film (ca. 1 μm) plated on an inverse opal structure based on the UV/vis switchable structure color of the sample. The top thin film acts as a protective layer to avoid the large deformation of the pore structure and the bottom inverse opal structure with refractive index/pore structure change that provides reversible structure color. Large, reversible, and rapid bandgap shift (ca. 60 nm, 2 s) of AZOIOs can be repeated more than 100 times under alternating UV/vis irradiation based on isomerization of high content of the azobenzene group. On-demand long-time preservation pattern can be obtained by the appearance of azobenzene's intrinsic color. The proof of concept for rewritable PC paper is demonstrated herein. Such inkless rewritable colorful paper paves a way for developing novel display technology.
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Affiliation(s)
- Junchao Liu
- Key Laboratory of Bio-inspired Materials and Interfaces Sciences, Technique Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yao Wang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Jingxia Wang
- Key Laboratory of Bio-inspired Materials and Interfaces Sciences, Technique Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- Center of Material Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 101407, China
- School of Future Technologies, University of Chinese Academy of Sciences, Beijing 101407, China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
| | - Tomiki Ikeda
- Key Laboratory of Bio-inspired Materials and Interfaces Sciences, Technique Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Materials and Interfaces Sciences, Technique Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- School of Future Technologies, University of Chinese Academy of Sciences, Beijing 101407, China
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Tseng HY, Chang LM, Lin KW, Li CC, Lin WH, Wang CT, Lin CW, Liu SH, Lin TH. Smart Window with Active-Passive Hybrid Control. MATERIALS 2020; 13:ma13184137. [PMID: 32957577 PMCID: PMC7560287 DOI: 10.3390/ma13184137] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 11/16/2022]
Abstract
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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Affiliation(s)
- Heng-Yi Tseng
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Li-Min Chang
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Kuan-Wu Lin
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Cheng-Chang Li
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Wan-Hsuan Lin
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Chun-Ta Wang
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
| | - Chien-Wen Lin
- Material and Chemical Research Laboratories of Industrial Technology Research Institute, Hsinchu 31040, Taiwan; (C.-W.L.); (S.-H.L.)
| | - Shih-Hsien Liu
- Material and Chemical Research Laboratories of Industrial Technology Research Institute, Hsinchu 31040, Taiwan; (C.-W.L.); (S.-H.L.)
| | - Tsung-Hsien Lin
- Department of Photonics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; (H.-Y.T.); (L.-M.C.); (K.-W.L.); (C.-C.L.); (W.-H.L.); (C.-T.W.)
- Correspondence: ; Tel.: +886-07-525-2000 (ext. 4442)
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Sharifimehr MR, Ayoubi K, Mohajerani E. Fabrication, morphological investigation and spectral characterization of nano-encapsulated azo dye-doped nematic liquid crystals. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113576] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Abstract
As buildings are a large energy user, it is important to not only reduce their consumption, but also have them generate their own electricity. Here, we describe a smart window that could reduce electricity consumption, normally used for air conditioning and lighting, by absorbing excess solar radiation with dichroic fluorescent dye molecules aligned in a switchable liquid crystal host and guiding the re-emitted light energy to the edges of the device, where it can be used to generate electricity via attached photovoltaic cells. The liquid crystals are responsive both to temperature changes and applied electrical fields. At higher temperatures, transmission decreases due to increased disorder in the liquid crystals, while the application of an electrical field increases transmission by effectively realigning the dyes for minimal absorption. Using alternative configurations, a window with a transparent rest state was also produced, in which transmission can be decreased by applying an electrical field; the thermal response remains identical.
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Timmermans GH, Saes BWH, Debije MG. Dual-responsive "smart" window and visually attractive coating based on a diarylethene photochromic dye. APPLIED OPTICS 2019; 58:9823-9828. [PMID: 31873626 DOI: 10.1364/ao.58.009823] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Controlling the intensity and manipulating the spectral composition of sunlight are critical for many devices including "smart" windows, greenhouses, and photomicroreactors, but these are also important in more decorative applications. Here, we use a diarylethene dye incorporated in a liquid crystal host to create a dual-responsive "smart" window regulated both by an electrical trigger and by specific wavelengths of light. By incorporating the same diarylethene dye in a polymerizable host and using inkjet printing, coatings can be made with complete freedom in the applied pattern design, although the electrical response is lost. The color change of the diarylethene dye can be controlled in simulated sunlight by concurrent light exposure from an LED source, allowing a manual override for outdoor use. Photoluminescence of the closed isomer of the diarylethene from the light guide edges could be used for lighting or electricity generation in a luminescent solar concentrator architecture.
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Talukder JR, Lin HY, Wu ST. Photo- and electrical-responsive liquid crystal smart dimmer for augmented reality displays. OPTICS EXPRESS 2019; 27:18169-18179. [PMID: 31252764 DOI: 10.1364/oe.27.018169] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 05/30/2019] [Indexed: 06/09/2023]
Abstract
A dual-stimuli polarizer-free dye-doped liquid crystal (LC) dimmer is demonstrated. The LC composition consists of photo-stable chiral agent, photosensitive azobenzene, and dichroic dye in a nematic host with positive dielectric anisotropy. Upon UV exposure, the LC directors and dye molecules turn from initially vertical alignment (high transmittance state) to twisted fingerprint structure (low transmittance state). The reversal process is accelerated by combining a longitudinal electric field to unwind the LC directors from twisted fingerprint to homeotropic state, and a red light to transform the cis azobenzene back to trans. This device can be used as a smart dimmer to enhance the ambient contrast ratio for augmented reality displays.
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15
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Meng C, Chen E, Wang L, Tang S, Tseng M, Guo J, Ye Y, Yan QF, Kwok H. Color-switchable liquid crystal smart window with multi-layered light guiding structures. OPTICS EXPRESS 2019; 27:13098-13107. [PMID: 31052839 DOI: 10.1364/oe.27.013098] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
We propose here a novel multi-layered waveguide liquid crystal (LC) smart window with full color rendering based on a polymer-network liquid crystal system. The inserted position of three-primary-color LED light bars is specially designed, which is parallel to the LC alignment to obtain a higher difference between transparent and scattering states. The optimal matching of polymer-network LC system is experimentally achieved by comparing several groups of LC and reactive mesogen materials. The prepared smart window is measured and analyzed in detail including optical/chromatic test, morphology characterization, and actual application effect. The proposed architecture opens up new prospects of flexible color switchable ability and synchronized full-color display for smart windows without limitations of slow LC response time and complicated field sequential driving scheme.
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