The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional c...The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.展开更多
Cholesteric liquid crystals(CLCs) have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architec...Cholesteric liquid crystals(CLCs) have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors' many years' research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.展开更多
Optical filters with different configurations based on cholesteric liquid crystals (CLCs) are designed. The central wavelength from CLCs can be tuned by the electric field or temperature. For the electric field tuni...Optical filters with different configurations based on cholesteric liquid crystals (CLCs) are designed. The central wavelength from CLCs can be tuned by the electric field or temperature. For the electric field tuning, the ITO is designed with circular patterns, which can make the tunable range 18 nm. For the temperature tuning, two-layer- CLC configurations are used. The experimental results indicate that a deepened or broadened bandgap from the CLC can be achieved by different handedness or concentrations of chiral dopants. The spectrum study is carried out.展开更多
Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The typ...Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The type of cholesteric mesomorphic azacrown ether have not been reported so far.展开更多
Versatile stimuli-responsive circularly polarized luminescent(CPL)materials have potential applications in information storage,security encryption,and intelligent displays.In this study,the Z/E isomerization of ultrav...Versatile stimuli-responsive circularly polarized luminescent(CPL)materials have potential applications in information storage,security encryption,and intelligent displays.In this study,the Z/E isomerization of ultraviolet(UV)-photosensitive achiralα-cyanostilbene derivative was used as an achiral dichroic dye(Switch)to drive the controllable CPL-active response in cholesteric liquid crystals(CLCs).Under irradiation by 365 nm UV light,the resulting CLCs-Z-Switch underwent a Z-to-E configuration isomerization as CLCs-E-Switch,accompanied by a decrease in its dichroic order parameter(SFvalue)from 0.15to 0.07.Although the quantum yield(QY)of CLCs-E-Switch increased from 8.1%(CLCs-Z-Switch)to 16.8%,the corresponding glumvalues of CPL emission decreased from+0.55/-0.57 to+0.37/-0.39 due to a decrease in the order of helical arrangement of E-Switch in E7 media.This study enables photosensitive CLCs-Switch to be applied for optical information storage devices.展开更多
The key to high-level encryption and anti-counterfeiting techniques is the storage of multiple levels of distinct information that can be individually and precisely addressed by certain stimuli.This continues to be a ...The key to high-level encryption and anti-counterfeiting techniques is the storage of multiple levels of distinct information that can be individually and precisely addressed by certain stimuli.This continues to be a formidable challenge as the concealed images or codes must be read with fast response and high resolution without cross-talk to the first layer of information.Here,we report a non-fluorescencebased strategy to establish responsive encryption labels taking advantage of solely tuning multiple optical patterns of cholesteric liquid crystal(CLC)microdroplets doped with light-driven molecular motors.The photo-triggered unidirectional rotation of the motor induced not only changes in the helical twist power value but the opposite helical orientation of the superstructure in CLCs as well,resulting in changes in both the structural color and the selective reflection of circularly polar light.The designed labels,which featured highly selective addressability of dual-level distinct information,good reversibility,and viewing angle-independence,were applied to build devices for daily practical use,demonstrating great potential in anti-counterfeiting technology and provide a versatile platform for enhanced data protection and encryption of authentic information.展开更多
We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal(PCLC)networks templated by the“wash-out/refill”method in the presence of organic compounds.The reflection colors were modulated by two ...We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal(PCLC)networks templated by the“wash-out/refill”method in the presence of organic compounds.The reflection colors were modulated by two key approaches,that is,the injection of mutually soluble organic fluids into a microfluidic channel and the diffusion of volatile organic compounds(VOCs).The reversible tuning of reflected colors with central wavelengths between~450 nm and~600 nm was achieved by alternative injection of nematic liquid crystal E7(n_(av)=1.64)and benzyl alcohol(n=1.54)using syringe pumps.The fascinating iridescence with reflection centers from~620 nm to~410 nm was presented from the volatilization and diffusion of alcohol as a model VOC.Additionally,the flow velocity of fluid and the diffusion time were adjusted to explore the underlying mechanism for the dynamic coloration of cholesteric networks.This work is expected to extend the study of PCLCs as a dynamically tunable optofluidic reflector,visually readable sensor,or compact anticounterfeit label in response to organic compounds.展开更多
Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopan...Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopant and monomer concentrations on the electro-optical properties, such as contrast ratio, driving voltage, hysteresis width and response time, are investigated. The reasons of electro-optical properties influenced by the concentrations of the materials are discussed. Through the proper material recipe, the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.展开更多
A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition tem...A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition temperature.展开更多
Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usuall...Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usually used as the exter nal stimulus source,which is not envir on ment-frie ndly enough.On the other hand,the mecha nical properties of CLCs are not strong eno ugh for these practical applications.Therefore,it still remains a challenge to endow the CLCs with visible light response and high mechanical properties at the same time.Herein,an axially chiral tetra-fluorinated binaphthyl azobenzene gelator(S-4F-AG)is synthesized.Upon 550 and 450 nm light irradiations,S-4F-AG exhibits excellent photo-switchable behaviors.Notably,the maximum con tent of c/s-isomer and its half-life are as high as 35%and 89 h in acet on itrile,respectively.A self-supporting CLC physical gel with a storage modulus around 104 Pa can be obtained when 3wt%S-4F-AG and 12wt%binaphthyl azobenzene derivative(dopant 2)are co-doped into a nematic LC host P0616A.This CLC physical gel exhibits a temperature-driven blue,green,and red reflection colors reversibly.Importantly,such three primary RGB colors can also be realized by adjusting the exposure time of 550 nm green light.This work lays a solid foundation for the applications ranging from information storage to high-tech anticounterfeit.展开更多
N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to pr...N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.展开更多
Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing ...Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart beams.Here,we mix cholesteric liquid crystals with dichroic black dye and a monomer.After UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated electrodes.Light patterns with arbitrary designs are projected dynamically.The switching time reaches several tens of milliseconds.This strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.展开更多
This Letter presents a new type of optical fiber probe used to detect temperature, whose structure is very simple.The optical fiber probe is filled with cholesteric liquid crystals(CLCs) whose reflected light varies w...This Letter presents a new type of optical fiber probe used to detect temperature, whose structure is very simple.The optical fiber probe is filled with cholesteric liquid crystals(CLCs) whose reflected light varies with temperature.The experimental results show that the proposed sensor can achieve a temperature sensitivity of 5.64 nm/°C in the temperature range of 18–40°C. The sensor has the advantages of simple structure, low cost, and easy mass manufacture. Its size is very tiny(the tapered structure, 125 μm in maximum diameter and <300 μm in length) and it is easy to integrate and measure. Meantime, the tapered structure of the probe is also ideal for measuring small samples such as cells and microfluidic channels, which will be a promising candidate for monitoring temperature fluctuations in small spaces.展开更多
We present a theoretical study of surface Tamm states localized at an interface that separates a semi-infinite isotropic left-handed metamaterial (LHM) and one-dimensional photonic crystal made of anisotropic in- de...We present a theoretical study of surface Tamm states localized at an interface that separates a semi-infinite isotropic left-handed metamaterial (LHM) and one-dimensional photonic crystal made of anisotropic in- definite metamaterial (IMM) (always-cutoff material). We discuss the dispersion properties of the Tamm states in different bandgaps and demonstrate that the cap layer, angular frequency, and arrangement of photonic crystal can provide flexible control for the dispersive properties of the Tamm states.展开更多
The dynamic manipulation of the helicity in a cholesteric helical superstructure could enable precise control over its physical and chemical properties, thus opening numerous possibilities for exploring multifunctiona...The dynamic manipulation of the helicity in a cholesteric helical superstructure could enable precise control over its physical and chemical properties, thus opening numerous possibilities for exploring multifunctional devices.When cholesteric material satisfies the sufficiently small bending elastic effect, an electrically induced deformation named the cholesteric heliconical superstructure is formed. Through theoretical and numerical analysis, we systematically studied the tunable helicity of the heliconical superstructure, including the evolution of the corresponding oblique angle and pitch length. To further confirm the optical properties, Berreman’s 4 × 4 matrix method was employed to numerically analyze the corresponding structure reflection under the dual stimuli of chirality and electric field.展开更多
Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable struc...Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable structures and synergistic properties is still on the way. Herein, we propose a simple and effective approach to create the multi-functional stimuli-responsive biomimetic devices with independently pre-programmable colorful visual patterns, complex geometries and morphable modes. The metal organic framework(MOF)-based composite film acts as a rigidity actuation substrate to support and mechanically guide the spatial configuration of the soft chiral nematic liquid crystal elastomer(CLCE) sheet. We can directly program the structural color of the CLCE sheet by adjusting the thickness distribution without tedious chemical modification. By using this coordination strategy, we fabricate an artificial flower, which exhibits a synergistic effect of both shape transformation and color change like paeonia ‘Coral Sunset’at different flowering stages, and can even perform different flowering behaviors by bending, twisting and curling petals. The assembled bionic flower is innovatively demonstrated to respond to local stimuli of humidity, heat or ultraviolet irradiation. Therefore, the spatial assembly of CLCE combined with functional MOF materials has a wide range of potential application in multi-functional integrated artificial systems.展开更多
Circularly polarized luminescence(CPL)has gained considerable attention in various systems and has rapidly developed into an emerging research field.To meet the needs of actual applications in diverse fields,a high lu...Circularly polarized luminescence(CPL)has gained considerable attention in various systems and has rapidly developed into an emerging research field.To meet the needs of actual applications in diverse fields,a high luminescence dissymmetry factor(glum)and tunable optical performance of CPL would be the most urgent pursuit for researchers.Accordingly,many emerging CPL materials and various strategies have been developed to address these critical issues.Emissive cholesteric liquid crystals(CLCs),that is,luminescent self-organized helical superstructures,are considered to be ideal candidates for constructing CPL-active materials,as they not only exhibit high glum values,but also enable flexible optical control of CPL.This review mainly summarizes the characteristics of CPL based on CLCs as the bulk phase doped with different emitters,including aggregated induced emission molecules,conventional organic small molecules,polymer emitters,metal-organic complex emitters,and luminescent nanoparticles.In addition,the recent significant progress in stimulus-responsive CPL based on emissive CLCs in terms of several types of stimuli,including light,electricity,temperature,mechanical force,and multiple stimuli is presented.Finally,a short perspective on the opportunities and challenges associated with CPL-active materials based on the CLC field is provided.This review is anticipated to offer new insights and guidelines for developing CLC-based CPL-active materials for broader applications.展开更多
基金This work was financially supported by the National High-Tech Research and Development Program of China (No. 2003AA327050).
文摘The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51573006,51573003,51203003,51303008,51302006,51402006,51272026,and 51273022)the Major Project of Beijing Science and Technology Program,China(Grant Nos.Z151100003315023 and Z141100003814011)the Fok Ying Tung Education Foundation,China(Grant No.142009)
文摘Cholesteric liquid crystals(CLCs) have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors' many years' research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61107059,61308052 and 61077047the Fundamental Research Funds for the Central Universitiesthe 111 Project of the Harbin Engineering University under Grant No B13015
文摘Optical filters with different configurations based on cholesteric liquid crystals (CLCs) are designed. The central wavelength from CLCs can be tuned by the electric field or temperature. For the electric field tuning, the ITO is designed with circular patterns, which can make the tunable range 18 nm. For the temperature tuning, two-layer- CLC configurations are used. The experimental results indicate that a deepened or broadened bandgap from the CLC can be achieved by different handedness or concentrations of chiral dopants. The spectrum study is carried out.
文摘Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The type of cholesteric mesomorphic azacrown ether have not been reported so far.
基金supported by the National Natural Science Foundation of China(21975118,92156014,52373188)。
文摘Versatile stimuli-responsive circularly polarized luminescent(CPL)materials have potential applications in information storage,security encryption,and intelligent displays.In this study,the Z/E isomerization of ultraviolet(UV)-photosensitive achiralα-cyanostilbene derivative was used as an achiral dichroic dye(Switch)to drive the controllable CPL-active response in cholesteric liquid crystals(CLCs).Under irradiation by 365 nm UV light,the resulting CLCs-Z-Switch underwent a Z-to-E configuration isomerization as CLCs-E-Switch,accompanied by a decrease in its dichroic order parameter(SFvalue)from 0.15to 0.07.Although the quantum yield(QY)of CLCs-E-Switch increased from 8.1%(CLCs-Z-Switch)to 16.8%,the corresponding glumvalues of CPL emission decreased from+0.55/-0.57 to+0.37/-0.39 due to a decrease in the order of helical arrangement of E-Switch in E7 media.This study enables photosensitive CLCs-Switch to be applied for optical information storage devices.
基金supported financially by the National Key R&D Program of China(grant no.2020YFE0100200)Science and Technology Projects in Guangzhou(grant no.202201000008)+2 种基金Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(grant no.2017B030301007)the Netherlands Ministry of Education,Culture and Science(Gravitation Program 024.001.035 to B.L.F.)S.X.acknowledges the fellowship of China Postdoctoral Science Foundation(grant no.2022M711224).
文摘The key to high-level encryption and anti-counterfeiting techniques is the storage of multiple levels of distinct information that can be individually and precisely addressed by certain stimuli.This continues to be a formidable challenge as the concealed images or codes must be read with fast response and high resolution without cross-talk to the first layer of information.Here,we report a non-fluorescencebased strategy to establish responsive encryption labels taking advantage of solely tuning multiple optical patterns of cholesteric liquid crystal(CLC)microdroplets doped with light-driven molecular motors.The photo-triggered unidirectional rotation of the motor induced not only changes in the helical twist power value but the opposite helical orientation of the superstructure in CLCs as well,resulting in changes in both the structural color and the selective reflection of circularly polar light.The designed labels,which featured highly selective addressability of dual-level distinct information,good reversibility,and viewing angle-independence,were applied to build devices for daily practical use,demonstrating great potential in anti-counterfeiting technology and provide a versatile platform for enhanced data protection and encryption of authentic information.
基金supported by the National Natural Science Foundation of China(Nos.62075186 and 62175206)the National Key R&D Program of China(No.2019YFA0905800)。
文摘We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal(PCLC)networks templated by the“wash-out/refill”method in the presence of organic compounds.The reflection colors were modulated by two key approaches,that is,the injection of mutually soluble organic fluids into a microfluidic channel and the diffusion of volatile organic compounds(VOCs).The reversible tuning of reflected colors with central wavelengths between~450 nm and~600 nm was achieved by alternative injection of nematic liquid crystal E7(n_(av)=1.64)and benzyl alcohol(n=1.54)using syringe pumps.The fascinating iridescence with reflection centers from~620 nm to~410 nm was presented from the volatilization and diffusion of alcohol as a model VOC.Additionally,the flow velocity of fluid and the diffusion time were adjusted to explore the underlying mechanism for the dynamic coloration of cholesteric networks.This work is expected to extend the study of PCLCs as a dynamically tunable optofluidic reflector,visually readable sensor,or compact anticounterfeit label in response to organic compounds.
基金Project partially supported by the National Natural Science Foundation of China (Grant Nos. 60736042, 60578035 and 50703039) and the Science Foundation of Jilin Province of China (Grant Nos. 20050520 and 20050321-2).
文摘Liquid crystals (LCs) and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopant and monomer concentrations on the electro-optical properties, such as contrast ratio, driving voltage, hysteresis width and response time, are investigated. The reasons of electro-optical properties influenced by the concentrations of the materials are discussed. Through the proper material recipe, the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.
文摘A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition temperature.
文摘Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usually used as the exter nal stimulus source,which is not envir on ment-frie ndly enough.On the other hand,the mecha nical properties of CLCs are not strong eno ugh for these practical applications.Therefore,it still remains a challenge to endow the CLCs with visible light response and high mechanical properties at the same time.Herein,an axially chiral tetra-fluorinated binaphthyl azobenzene gelator(S-4F-AG)is synthesized.Upon 550 and 450 nm light irradiations,S-4F-AG exhibits excellent photo-switchable behaviors.Notably,the maximum con tent of c/s-isomer and its half-life are as high as 35%and 89 h in acet on itrile,respectively.A self-supporting CLC physical gel with a storage modulus around 104 Pa can be obtained when 3wt%S-4F-AG and 12wt%binaphthyl azobenzene derivative(dopant 2)are co-doped into a nematic LC host P0616A.This CLC physical gel exhibits a temperature-driven blue,green,and red reflection colors reversibly.Importantly,such three primary RGB colors can also be realized by adjusting the exposure time of 550 nm green light.This work lays a solid foundation for the applications ranging from information storage to high-tech anticounterfeit.
基金Supported by the National Natural Science Foundation of China( No. 2 9974 0 2 3)
文摘N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.
基金This work was supported by the National Key Research and Development Program of China(No.2022YFA1203703)the National Natural Science Foundation of China(NSFC)(No.62035008)the Fundamental Research Funds for the Central Universities(No.021314380233).
文摘Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart beams.Here,we mix cholesteric liquid crystals with dichroic black dye and a monomer.After UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated electrodes.Light patterns with arbitrary designs are projected dynamically.The switching time reaches several tens of milliseconds.This strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.
基金supported by the National Natural Science Foundation of China (Nos. U1531102 and 61811530061)the Chifeng University Service Economic and Social Development Application Project Foundation of Chifengthe Fundamental Research Funds for the Central Universities
文摘This Letter presents a new type of optical fiber probe used to detect temperature, whose structure is very simple.The optical fiber probe is filled with cholesteric liquid crystals(CLCs) whose reflected light varies with temperature.The experimental results show that the proposed sensor can achieve a temperature sensitivity of 5.64 nm/°C in the temperature range of 18–40°C. The sensor has the advantages of simple structure, low cost, and easy mass manufacture. Its size is very tiny(the tapered structure, 125 μm in maximum diameter and <300 μm in length) and it is easy to integrate and measure. Meantime, the tapered structure of the probe is also ideal for measuring small samples such as cells and microfluidic channels, which will be a promising candidate for monitoring temperature fluctuations in small spaces.
基金supported by the National Natural Science Foundation of China under Grant No. 11274225
文摘We present a theoretical study of surface Tamm states localized at an interface that separates a semi-infinite isotropic left-handed metamaterial (LHM) and one-dimensional photonic crystal made of anisotropic in- definite metamaterial (IMM) (always-cutoff material). We discuss the dispersion properties of the Tamm states in different bandgaps and demonstrate that the cap layer, angular frequency, and arrangement of photonic crystal can provide flexible control for the dispersive properties of the Tamm states.
基金supported by the National Natural Science Foundation of China(Nos.61822504 and 51873060)the Shanghai Rising Star Program(No.17QA1401100)the Fundamental Research Funds for the Central Universities(No.JKM012016032).
文摘The dynamic manipulation of the helicity in a cholesteric helical superstructure could enable precise control over its physical and chemical properties, thus opening numerous possibilities for exploring multifunctional devices.When cholesteric material satisfies the sufficiently small bending elastic effect, an electrically induced deformation named the cholesteric heliconical superstructure is formed. Through theoretical and numerical analysis, we systematically studied the tunable helicity of the heliconical superstructure, including the evolution of the corresponding oblique angle and pitch length. To further confirm the optical properties, Berreman’s 4 × 4 matrix method was employed to numerically analyze the corresponding structure reflection under the dual stimuli of chirality and electric field.
基金The financial support of this work by the Natural Science Foundation of Hebei province of China (No. F2020202015)。
文摘Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable structures and synergistic properties is still on the way. Herein, we propose a simple and effective approach to create the multi-functional stimuli-responsive biomimetic devices with independently pre-programmable colorful visual patterns, complex geometries and morphable modes. The metal organic framework(MOF)-based composite film acts as a rigidity actuation substrate to support and mechanically guide the spatial configuration of the soft chiral nematic liquid crystal elastomer(CLCE) sheet. We can directly program the structural color of the CLCE sheet by adjusting the thickness distribution without tedious chemical modification. By using this coordination strategy, we fabricate an artificial flower, which exhibits a synergistic effect of both shape transformation and color change like paeonia ‘Coral Sunset’at different flowering stages, and can even perform different flowering behaviors by bending, twisting and curling petals. The assembled bionic flower is innovatively demonstrated to respond to local stimuli of humidity, heat or ultraviolet irradiation. Therefore, the spatial assembly of CLCE combined with functional MOF materials has a wide range of potential application in multi-functional integrated artificial systems.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2017YFA0204504)the National Natural Science Foundation of China(51873221,52073292,51673207,and 51373183)Chinese Academy of Sciences and Dutch Research Project(1A111KYSB20190072)。
基金National Natural Science Foundation of China,Grant/Award Numbers:52073017,51773009FundamentalResearch Funds for the Central Universities+1 种基金NationalNatural Science Foundation of China,Grant/Award Numbers:52073017,51773009FundamentalResearch Funds for the Central Universities。
文摘Circularly polarized luminescence(CPL)has gained considerable attention in various systems and has rapidly developed into an emerging research field.To meet the needs of actual applications in diverse fields,a high luminescence dissymmetry factor(glum)and tunable optical performance of CPL would be the most urgent pursuit for researchers.Accordingly,many emerging CPL materials and various strategies have been developed to address these critical issues.Emissive cholesteric liquid crystals(CLCs),that is,luminescent self-organized helical superstructures,are considered to be ideal candidates for constructing CPL-active materials,as they not only exhibit high glum values,but also enable flexible optical control of CPL.This review mainly summarizes the characteristics of CPL based on CLCs as the bulk phase doped with different emitters,including aggregated induced emission molecules,conventional organic small molecules,polymer emitters,metal-organic complex emitters,and luminescent nanoparticles.In addition,the recent significant progress in stimulus-responsive CPL based on emissive CLCs in terms of several types of stimuli,including light,electricity,temperature,mechanical force,and multiple stimuli is presented.Finally,a short perspective on the opportunities and challenges associated with CPL-active materials based on the CLC field is provided.This review is anticipated to offer new insights and guidelines for developing CLC-based CPL-active materials for broader applications.