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- 2018
- 3D display
- holographic display
- Augmented reality
- volumetric display
- liquid crystal
- blocking electrodes
- impedance spectroscopy
- liquid crystals
- electric conductivity
- Optoelectronic Information Science and Engineering
- Shanghai Jiao Tong University
- South Ural State University
- Technical University of Darmstadt
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Opposite Self-Folding Behavior of Polymeric Photoresponsive Actuators Enabled by a Molecular Approach
摘要： The ability to obtain 3D polymeric objects by a 2D-to-3D shape-shifting method is very appealing for polymer integration with different materials, from metals in electronic devices to cells in biological studies. Such functional reshaping can be achieved through self-folding driven by a strain pattern designed into the molecular network. Among polymeric materials, liquid crystalline networks (LCNs) present an anisotropic molecular structure that can be exploited to tailor internal strain, resulting in a natural non-planar geometry when prepared in the form of flat films. In this article, we analyze the influence of different molecular parameters of the monomers on the spontaneous shape of the polymeric films and their deformation under different stimuli, such as heating or light irradiation. Modifying the alkilic chains of the crosslinkers is a simple and highly effective way to increase the temperature sensitivity of the final actuator, while modifying ester orientation on the aromatic core interestingly acts on the bending direction. Combining such effects, we have demonstrated that LCN stripes made of different monomeric mixtures originate complex non-symmetric deformation under light activation, thus opening up new applications in photonic and robotics.
关键词： photonic actuators,liquid crystalline networks,curvature design,photoresponsive polymers,shape-changing materials
更新于2025-11-21 11:24:58
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Unraveling the electrical properties of solution-processed copper iodide thin films for CuI/n-Si solar cells
摘要： The effects of temperature and liquid-phase iodination on the electrical property of spin coated CuI thin films have been investigated in details. The XRD study indicates that CuI thin films are polycrystalline in nature and I-doping enhances the crystal quality and size of the films. The SEM images show that the surface uniformity of the CuI thin films increases due to I-doping. The doping of iodine increases the conductivity as well as carrier concentration and mobility of the films as confirmed by Hall study. The temperature dependent resistivity of CuI film shows a sharp fall of resistivity at ~80 °C for un-doped films whereas this behavior disappears for I-doped films. The optical transmittance and band gap of the I-doped films also increases indicating high degeneracy of the films. These findings imply that I-doped spin coated CuI thin films are potential candidate for the solution-processed CuI/n-Si solar cells.
关键词： liquid-phase I-doped,spin coat,CuI thin films,switching-behavior,electrical properties
更新于2025-11-21 11:18:25
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Liquid Crystal-Induced Myoblast Alignment
摘要： The ability to control cell alignment represents a fundamental requirement toward the production of tissue in vitro but also to create biohybrid materials presenting the functional properties of human organs. However, cell cultures on standard commercial supports do not provide a selective control on the cell organization morphology, and different techniques, such as the use of patterned or stimulated substrates, are developed to induce cellular alignment. In this work, a new approach toward in vitro muscular tissue morphogenesis is presented exploiting liquid crystalline networks. By using smooth polymeric films with planar homogeneous alignment, a certain degree of cellular order is observed in myoblast cultures with direction of higher cell alignment corresponding to the nematic director. The molecular organization inside the polymer determines such effects since no cell organization is observed using homeotropic or isotropic samples. These findings represent the first example of cellular alignment induced by the interaction with a nematic polymeric scaffold, setting the stage for new applications of liquid crystal polymers as active matter to control tissue growth.
关键词： liquid crystalline alignments,liquid crystalline network,cell alignment,biomaterials,muscular tissue engineering
更新于2025-11-21 11:01:37
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Alignment of liquid crystals using Langmuir?Blodgett films of unsymmetrical bent-core liquid crystals
摘要： The properties of the thin films of liquid crystal (LC) molecules can be governed easily by external fields. The anisotropic structure of the LC molecules has a large impact on the electrical and optical properties of the film. The Langmuir monolayer (LM) of LC molecules at the air–water interface is known to exhibit a variety of surface phases which can be transferred onto a solid substrate using the Langmuir?Blodgett (LB) technique. Here, we have studied the LM and LB films of asymmetrically substituted bent-core LC molecules. The morphology of LB film of the molecules is found to be a controlling parameter for aligning bulk LC in the nematic phase. It was found that the LB films of the bent-core molecules possessing defects favour the planar orientation of nematic LC, whereas the LB films with fewer defects show homeotropic alignment. The defect in LB films may introduce splay or bend distortions in the nematic near the alignment layer which can govern the planar alignment of the bulk LC. The uniform layer of LB film facilitates the molecules of nematic to anchor vertically due to a strong van der Waals interaction between the aliphatic chains leading to a homeotropic alignment.
关键词： field emission scanning electron microscope,atomic force microscope,Langmuir?Blodgett film,liquid crystals,Brewster angle microscopy,Langmuir monolayer
更新于2025-11-21 11:01:37
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Two-dimensional beta-lead oxide quantum dots
摘要： In recent years, black-phosphorus-analogue (BPA) two-dimensional (2D) materials have been explored to demonstrate promising optoelectronic performances and distinguished ambient stabilities, holding great promise in practical applications. Here, one new kind of BPA material, orthorhombic β-PbO quantum dots (QDs), is successfully fabricated by a facile liquid phase exfoliation (LPE) technique. The as-prepared β-PbO QDs show a homogeneous distribution of the lateral size (3.2 ± 0.9 nm) and thickness (2.5 ± 0.5 nm), corresponding to 4 ± 1 layers. The carrier dynamics of β-PbO QDs was systematically investigated via a femtosecond resolution transient absorption approach in the visible wavelength regime and it was clarified that two decay components were resolved with a decay time of τ1 = 2.3 ± 0.3 ps and τ2 = 87.9 ± 6.0 ps, respectively, providing important insights into their potential applications in the field of ultrafast optics, nanomechanics and optoelectronics. As a proof-of-concept, β-PbO QDs were, for the first time to our knowledge, fabricated as a working electrode in a photoelectrochemical (PEC)-typed photodetector that exhibits significantly high photocurrent density and excellent stability under ambient conditions.
关键词： photoelectrochemical photodetector,β-PbO quantum dots,carrier dynamics,liquid phase exfoliation
更新于2025-11-19 16:56:42
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Assembly structure and free energy change of a chromonic liquid crystal formed by a perylene dye
摘要： The nematic (chromonic N) and isotropic phases formed by aqueous solutions of a perylene dye are investigated by x-ray diffraction and visible light absorption spectroscopy. X-ray diffraction shows that the molecules assemble into columns one molecule wide. The change in the visible absorption spectrum with concentration indicates that the molecules stack in a more or less isodesmic manner and that the free energy change associated with the addition or removal of a single molecule from a stack is 16–20 kBT. This range is appreciably higher than those of any previously-measured simple chromonic systems, i.e. those with single molecule-wide columns. It is suggested that the large free energy change promotes the formation of extremely long columns of molecules, and in turn leads to the low concentration at which mesophase formation takes place.
关键词： chromonic,isodesmic,scission energy,perylene dye,assembly structure,lyotropic chromonic,Liquid crystals
更新于2025-11-19 16:56:35
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Light-Emitting Porphyrin Derivative Obtained from a Subproduct of the Cashew Nut Shell Liquid: A Promising Material for OLED Applications
摘要： In this work, the meso-tetra[4-(2-(3-n-pentadecylphenoxy)ethoxy]phenylporphyrin (H2P), obtained from the cashew nut shell liquid (CNSL), and its zinc (ZnP) and copper (CuP) metallic complexes, were applied as emitting layers in organic light emitting diodes (OLEDs). These compounds were characterized via optical and electrochemical analysis and the electroluminescent properties of the device have been studied. We performed a cyclic voltammetry analysis to determine the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels for the porphyrins, in order to select the proper materials to assemble the device. H2P and ZnP presented fluorescence emission band in the red region, from 601 nm to 718 nm. Moreover, we verified that the introduction of bulky substituents hinders the π–π stacking, favoring the emission in the film. In addition, the strongest emitter, ZnP, presented a threshold voltage of 4 V and the maximum irradiance of 10 μW cm?2 with a current density (J) of 15 mA cm?2 at 10 V. The CuP complex showed to be a favorable material for the design of OLEDs in the infrared. These results suggest that the porphyrins derived from a renewable source, such as CNSL, is a promising material to be used in organic optoelectronic devices such as OLEDs.
关键词： cashew nut shell liquid,porphyrins,OLEDs,electroluminescence,photoluminescence
更新于2025-11-19 16:46:39
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High dielectric polymer and its application on electro-optical Kerr effect of blue phase liquid crystal
摘要： We present a high-dielectric polymer with a lateral ?uorine group, and its dielectric constant exhibits larger than 20 at 1 kHz. This well-soluble polymer can solely stabilize blue phase liquid crystals (BPLCs) while reducing the operating voltage by 30% and increasing the Kerr constant by nearly 70.6%. The in?uence of the polymer’s dielectric property on the operating voltage is investigated based on the potential distribution. The theoretical result predicts that the operation voltage can be further reduced by 50% when the dielectric constant of the chiral dopant is the same as the high-dielectric polymer. The potential application of high-dielectric materials for the improvement of BPLC devices is foreseeable.
关键词： Kerr constant,blue phase liquid crystals,high-dielectric polymer,electro-optical Kerr effect,operating voltage
更新于2025-11-14 17:28:48
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Electro-Thermal Formation of Uniform Lying Helix Alignment in a Cholesteric Liquid Crystal Cell
摘要： We demonstrated previously that the temperature of a sandwich-type liquid crystal cell with unignorable electrode resistivity could be electrically increased as a result of dielectric heating. In this study, we take advantage of such an electro-thermal effect and report on a unique electric-field approach to the formation of uniform lying helix (ULH) texture in a cholesteric liquid crystal (CLC) cell. The technique entails a hybrid voltage pulse at frequencies f1 and, subsequently, f2, which are higher and lower than the onset frequency for the induction of dielectric heating, respectively. When the cell is electrically sustained in the isotropic phase by the voltage pulse of V = 35 Vrms at f1 = 55 kHz or in the homeotropic state with the enhanced ionic effect at V = 30 Vrms and f1 = 55 kHz, our results indicate that switching of the voltage frequency from f1 to f2 enables the succeeding formation of well-aligned ULH during either the isotropic-to-CLC phase transition at f2 = 1 kHz or by the electrohydrodynamic effect at f2 = 30 Hz. For practical use, the aligning technique proposed for the first time in this study is more applicable than existing alternatives in that the obtained ULH is adoptable to CLCs with positive dielectric anisotropy in a simple cell geometry where complicated surface pretreatment is not required. Moreover, it is electrically switchable to other CLC textures such as Grandjean planar and focal conic states without the need of a temperature controller for the phase transition, the use of ion-rich LC materials, or mechanical shearing for textural transition.
关键词： cholesteric liquid crystals,uniform lying helix,dielectric heating
更新于2025-11-14 17:28:48
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Rapid gas-liquid detonation synthesis of core-shell structural graphite coated TiO2 nanoparticles
摘要： Here we demonstrate a simple, rapid for the controlled synthesis of core-shell structural graphite coated TiO2 nanoparticle (TiO2@G), which are directly prepared by detonation chemical decomposition of the gas-liquid mixture of CH4, O2, C6H6 and TiCl4 in milliseconds. Various techniques, including XPS, TEM, XRD and Raman were employed to investigate the products. It is found that the sphere, good disperse mixed crystal TiO2 nanoparticles with crystal size of 10–30 nm were coated with thick graphite layers. Based on Zeldovich Neuman-Doring (ZND) model, the detonation synthesis mechanism of core-shell structure TiO2@G is discussed. This rapid synthesis method can be extended to the preparation of other core-shell materials.
关键词： Gas-liquid detonation,Graphite coated TiO2,Core-shell structure,Composite materials,Formation mechanism
更新于2025-11-14 17:04:02