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- 2019
- polycrystalline ferrite-garnet
- magnetoplasmonic crystals
- magnetooptical effects
- deposition
- ion-beam methods
- sputtering
- plasmon resonance
- Physics
- Moscow Technological University
- Moscow State University
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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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Crystallographically oriented porous ZnO nanostructures with visible-blind photoresponse: controlling the growth and optical properties
摘要： We have grown catalyst-free crystallographically oriented porous ZnO nanostructures by pulsed laser deposition (PLD) method. The deposition was performed in two stages for each sample. In the first stage, self-seeding of ZnO was performed on the quartz substrate, and the angle of deposition (seeding-angle) was varied. Thus, the growth of seeds is different here. In the second stage, the deposition was performed at a glancing angle (at 85?) for the fixed duration of time to grow the nanostructures. These PLD-grown nanostructures acquire highly oriented wurtzite structure. We find that the seeding-angle during the first stage is the determining deposition parameter which influences the growth and other properties of these nanostructures in a controllable manner. The variation in seeding-angle systematically tunes the crystallographic orientation and porosity, which in turn influences the visible-blindness and ultraviolet (UV) photoresponse of these nanonetworks. Here we report the growth of completely defect-free crystallographically oriented nanostructures with necessary porosity for application in visible-blind UV photodetection.
关键词： Crystalline ZnO,catalyst-free ZnO,glancing angle deposition (GLAD),seeding,pulsed laser deposition (PLD),nanostructures
更新于2025-11-21 11:03:13
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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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Cu(In,Ga)Se2 monograin powders with different Ga content for solar cells
摘要： Monograin layer (MGL) solar cell technology based on CuIn1-xGaxSe2 (CIGSe) monograin powder crystals is a promising approach for the future low-cost production of flexible solar panels. In this study, CuIn1-xGaxSe2 monograin powders (0 ≤ x ≤ 1) were prepared from binary compounds in the liquid phase of potassium iodide as flux material in evacuated quartz ampoules at 720 °C. The crystal structure and the lattice parameters of the CIGSe monograin powder crystals were determined by using X-ray diffraction analysis. A linear decrease of the lattice parameters with increasing Ga concentration was detected. The photoluminescence (PL) spectra of the CIGSe crystals were dominated by the edge emission band that shifted towards higher energies with increasing Ga content. Moreover, additional deep PL band (below 1.0 eV) appeared for Ga contents above x = 0.21 showing higher relative intensity with increasing Ga content. The effective bandgap energy of the CIGSe monograin powder materials ranged from 1.0 eV to 1.68 eV as the [Ga]/([In] + [Ga]) ratio increased from 0 to 1.0. An efficiency of 12.8% (active area) was obtained with the MGL solar cell based on CuIn1-xGaxSe2 monograin powder with Ga content of x = 0.21.
关键词： Cu(In,Ga)Se2,Solar cell,Crystalline powder,Crystal growth
更新于2025-11-21 10:59:37
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Defining the composition and electronic structure of large-scale and single-crystalline like Cs2AgBiBr6 films fabricated by capillary-assisted dip-coating method
摘要： Owning the merits of both lead-free and air-stable, the double-perovskite Cs2AgBiBr6 has attracted increasing attention, but suffers low visible-light absorption coefficient due to its large indirect bandgap. Moreover, the electronic structure of its synthesized films has not been explored clearly yet. In this work, we developed a general and promising method to fabricate continuous, uniform and highly orientated Cs2AgBiBr6 films in large scale on various substrates through capillary-assisted dip-coating method. Strikingly, those optimized films are single crystalline verified by 4-scan XRD. Its electronic structure was carefully studied independently by multi-photo-physical characterizations. Its bandgap can be tuned from 2.65 to 2.25 eV by changing the substrate temperature in growth from 40 to 160 °C. Essentially, their work-function (WF) was determined at ~5.01 eV and WF-VBM is around 2 eV. This novel band structure with typical n-type characteristic, was further confirmed by DFT calculations, which reveals that the Cs interstitials and Br vacancies derived deep defect levels were fixed around its Fermi level, closer to the conduction band. This conclusion is different from its widely accepted p-type feature, but definitely deepens our understanding of this material and inspires us to find more valuable strategies of modulating its band structure and optoelectronic properties.
关键词： Single-crystalline perovskite films
更新于2025-11-20 15:33:11
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Controlling porosity and ultraviolet photoresponse of crystallographically oriented ZnO nanostructures grown by pulsed laser deposition
摘要： We have synthesized a series of porous nanostructures of c-axis oriented wurtzite ZnO using glancing angle pulsed laser deposition. During deposition, the oxygen partial pressure (PO2) was varied to study the effects on growth, porosity and optical properties. With varied PO2 the growth of nanostructure changes gradually without losing its crystallographic orientation. The variation in PO2 causes systematic change in porosity of these nanostructures, which strongly influences ultraviolet photoresponse. These results show that the parameters such as surface morphology, growth and porosity as well as the optoelectronic properties can be controlled by variation in PO2 without compromising the crystalline structure.
关键词： Crystalline nanostructures,Photoresponse,Porosity,Ultraviolet,Glancing angle pulsed laser deposition
更新于2025-11-19 16:56:42
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Copper-Based Volumetric Filler Dedicated for Ag Paste for Depositing the Front Electrodes by Printing on Solar Si Cells
摘要： In this work we present research results on a new paste NPCuXX (where: NP—new paste, CuXX—component, XX—a modifier consisting of Ni and other important elements) based on a copper composite (CuXX) for fabrication of front electrodes in silicon solar cells. The CuXX composite is obtained by chemical processing of copper powder particles and can be used in two ways: as an additive to commercially available paste or as a base material for a new paste, NPCuXX. The CuXX offers the possibility to exchange up to 30 and 50 wt.% Ag into Cu, which significantly decreases the solar cells material costs, and therefore, the overall solar cell price. Emphasis was placed on a proper mass suitable fabrication process of the CuXX component. The NPCuXX paste has been applied both to conventional cell structures such as aluminum-back surface field (Al-BSF) and passivated emitter and rear contact (PERC), and finally solar cells with front electrodes deposited by screen-printing method were fabricated and characterized by current-voltage techniques. This paper reports the first implementation of the copper volumetric material into a screen print paste used in a high-temperature metallization process to fabricate the front contacts of Si solar cells with a highest fill factor of 77.92 and 77.69% for the abovementioned structures, respectively.
关键词： crystalline silicon solar cells,front electrode,copper-based volumetric filler
更新于2025-11-14 17:04:02
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Effect of thermal annealing on the crystalline structure of PVDF/PMMA-modified graphene nanocomposites
摘要： Poly(vinylidene fluoride)-based nanocomposite films with different loadings of PMMA-modified graphene sheets were prepared by a solution-mixing and solvent casting method. The prepared films were annealed at three different temperatures and the crystalline structures of the samples were investigated. X-ray diffraction data confirmed the PMMA-modified graphene nanosheets enhanced the preferential b-crystalline structure when increasing the annealing temperature to 90 (cid:1)C, while increasing the annealing temperature to 120 (cid:1)C led to a b ! c phase conversion. The tendency of the graphene sheets to restack by increasing the annealing temperature was confirmed by XRD. The PMMA-modified graphene sheets, however, didn’t showa nucleating effect on the PVDF crystallizationduring DSC cooling scans.
关键词： Graphite,crystalline structure,graphene,PVDF,modification of graphene,b crystalline phase,PMMA
更新于2025-09-23 15:23:52
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A Novel Phytantriol-Based Lyotropic Liquid Crystalline Gel for Efficient Ophthalmic Delivery of Pilocarpine Nitrate
摘要： The purpose of this paper was to investigate the potential of liquid crystalline (LC) gels for ophthalmic delivery, so as to enhance the bioavailability of pilocarpine nitrate (PN). The gels were prepared by a vortex method using phytantriol and water (in the ratio of 73:27 w/w). Their inner structures were con?rmed by crossed polarized light microscopy, small-angle X-ray scattering, attenuated total re?ectance-Fourier transform infrared spectrum, and rheology. The in vitro release studies revealed that PN could keep sustained release from the gels over a period of 12 h. The ex vivo apparent permeability coef?cient of the gels demonstrated a 3.83-folds (P < 0.05) increase compared with that of eye drops. The corneal hydration levels of the gel maintained in the normal range of 79.46 ± 2.82%, hinting that the gel could be considered non-damaging and safe to the eyes. Furthermore, in vivo residence time evaluation suggested that a better retention performance of LC gel was observed in rabbit’s eyes compared to eye drops. In vivo ocular irritation study indicated that LC gel was nonirritant and might be suitable for various eye applications. In conclusion, LC gels might represent a potential ophthalmic delivery strategy to overcome the limitations of eye drops.
关键词： ophthalmic delivery,pilocarpine nitrate,cubic phase,liquid crystalline gel,phytantriol
更新于2025-09-23 15:23:52
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Voltage Stimulated Anion Binding of Metallo-Porphyrin Induced Crystalline 2D Nanoflakes
摘要： Voltage stimulated redox active materials received significant attention in the field of organic electronics and sensor technology. Consequently, such stimuli responsive materials triggered the formation of crystalline nanostructures facilitates the design of efficient smart devices hitherto unknown. Thus, we reported free base and metallo- tetratolylporphyrin linked ferrocene derivatives (H2TTP-Fc and ZnTTP-Fc) undergo distinct proton/anion binding mechanism in CHCl3 during bulk electrolysis at applied voltage of 1.4 V followed by nanospheres and crystalline 2D nanoflakes formation via MVD approach. Cyclic voltammetry and UV-Vis absorption studies of H2TTP-Fc and ZnTTP-Fc revealed the cation (H+)/anion (Cl-) binding affinity towards free ‘N’ atoms and Zn leads [H4TTP-Fc]+Cl- and H+[(Cl)ZnTTP-Fc]- thereby improvement in current and charge generation compared to initial state. SEM and TEM images revealed the nanospheres and 2D nanoflakes with average diameter of 50 – 200 nm and 0.2 - 1 μm. x-ray diffraction analysis suggest that protonated H2TTP-Fc aggregates exhibit amorphous nature, while H+[(Cl)ZnTTP-Fc]- revealed crystalline nature from layer-by-layer arrangement of nanoflakes assisted by π-π stacking and ion-dipole interactions. Hence, voltage responsive anion binding of metallo-porphyrins unique observation offer remarkable design of smart organic materials for sensors and biological applications.
关键词： anion binding,crystalline nanoflakes,metallo-porphyrin,self-assembly,bulk electrolysis
更新于2025-09-23 15:23:52