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Three-dimensional Nanoscale Mapping of Porosity in Solution-Processed ITO Multilayer Thin Films for Patternable Transparent Electrodes
摘要： Indium tin oxide (ITO) films constitute components of many layered heterostructures used for emergent technologies beyond conventional optoelectronics. Compositional and morphological changes have a direct impact on the device’s performance. Hence control over the morphology with advanced multimodal characterization approaches are required to evaluate the devices. Herein multilayer ITO films deposited by spin coating were quantified in nanoscale detail in three dimensions by combining results from depth-sensitive neutron reflectometry (NR), non-contact topographic AFM images and cross-sectional SEM images. Films with different number of deposited layers were visually transparent even though the topmost layer was as high as 60% porous, with porosity gradually decreasing as the number of the underneath sublayers increased. Surface and interfacial roughness through the total film and individual layer thickness were obtained. NR data also furnished quantitative depth information on the films chemical composition and layer-by-layer bulk density, which has never been obtained before, providing a way to monitor and ultimately control the sheet resistivity via the pore network. When the same formulation is used for inkjet printing patterns, the larger pores disappear and the optical properties are improved to >90% transmittance at all visible wavelengths. All 5L films achieved sheet resistivities as low as 10-2 ?-cm and can therefore be used as patternable transparent electrodes for many devices including liquid crystal displays.
关键词： thin multilayer film,neutron reflectometry,depth density distribution,neutron absorption reflectometry,Indium tin oxide,porosity,structure chemical depth profile,off-specular neutron scattering,layer by layer deposition
更新于2025-11-19 16:56:35
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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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Robust Janus fibrous membrane switchable infrared radiation properties for potential building thermal management application
摘要： Buildings heating and cooling consumes a large part of global energy, contributing to aggravating the global warming and energy crisis. It is strongly desired but still lacking in realizing heating and cooling functions within the same material without intensive energy input. Herein, a Janus thermal management membrane with trilayer structure has been prepared by using the ZnO nanorods array-coated cellulose (ZnO-NRs@cellulose), ultralong MnO2 nanowires (UL-MnO2-NWs) and silver nanowires (Ag-NWs) as building blocks. The ZnO-NRs@cellulose fiber layer with rough surface was fabricated by a hydrothermal progress based on the controlled growth of ZnO nanorods on cellulose surfaces. Subsequently, the hydrothermally synthesized UL-MnO2-NWs and Ag-NWs were filtered onto the ZnO-NRs@cellulose layer in turn, forming laminated Janus membrane. The Janus membrane exhibited asymmetric radiation properties on each side: the ZnO-NRs@cellulose side of the Janus membrane shows high solar radiation reflectivity and high infrared emissivity to minimize heat input from sun and enhance the heat dissipation in hot environment, while Ag-NWs side of that exhibits relatively high solar radiation absorption rate and low infrared emissivity for enhancing heat input from sun and reducing the heat radiation loss in cold environment. The introduction of UL-MnO2-NWs and Ag-NWs into the laminated Janus membrane endows the membrane with high tensile stress of 61.4 MPa. Moreover, the strong compatible entanglement among three layers of the Janus membrane causes the satisfactory interface stability. Due to the special asymmetric radiation performance, excellent interfacial compatibility, and high mechanical stability, such Janus membrane might be potential useful in building energy saving, personal thermal management and other facilities.
关键词： solar radiation,infrared radiation,laminated structure,MnO2 nanowire,Ag nanowire,Janus membrane
更新于2025-11-19 16:56:35
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Synthesis, Crystal Structure, and Photocatalytic Properties of a Zinc(II) Coordination Polymer Based on 3-Hydroxy-2-pyridinecarboxylic Acid
摘要： The zinc(II) compound, [Zn3(HL)6]n (1) (H2L = 3-hydroxypyridine-2-carboxylic acid) was synthesized by a solvothermal reaction of Zn(NO3)2·6H2O and 3-hydroxypyridine-2-carboxylic acid as raw materials. The structure of complex 1 was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, as well as powder X-ray diffraction. X-ray structure analysis demonstrates that the complex crystallizes in the monoclinic system, space group P21/n. There are three zinc ions in the asymmetric unit, which are either five-coordinate or six-coordinate. The asymmetric units are further bridged by the carboxylate of the organic ligands, featuring a 2D framework. The solid state diffuse-reflectance UV/Vis spectra reveals that complex 1 has semiconducting nature with the energy bandgap (Eg) estimated to be 3.11 eV. The photocatalytic properties of complex 1 in degradation of organic dyes were further investigated. Results showed that the complex could degrade 54 % of the dye methylene blue solution within 120 min under UV irradiation light and reused for five times without the decline of the photocatalytic activity.
关键词： Crystal structure,Photocatalytic properties,Zinc,3-Hydroxypyridine-2-carboxylic acid,Solvothermal reaction,Coordination polymer
更新于2025-11-19 16:56:35
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Synchronized “Click” and Templated Synthesis of a Fluorescent Pyrene Crown Ether
摘要： The reaction of 6,8-bisethynylpyrene-2-carboxylic acid methyl ester with 1-azido-2-(2-(2-azidoethoxy)ethoxy)ethoxy)ethane using standard “click” chemistry produced a 1+1 crown ether (CPYR). The copper ions used both catalyse the reaction and provide a template for ensuring smooth cyclisation. The X-ray crystal structure of the compound reveals the two triazole groups are non-coplanar with the pyrene moiety. The triazole groups are more co-planar with the pyrene subunit in the first-excited singlet state as revealed by a density functional theory (DFT) calculated molecular structure (B3LYP, 6-311G). Partially structured emission observed in acetonitrile is consistent with the calculation result. In acetonitrile solution the macrocycle CPYR interacts with a Na+ ion to form a complex in which the ion binds with the crown and the pyrene residue.
关键词： pyrene,structure,click,binding,crown ether
更新于2025-11-19 16:46:39
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Admittance of Organic LED Structures with an Emission YAK-203 Layer
摘要： The current-voltage characteristics and admittance of multilayer structures for organic LEDs based on the PEDOT:PSS/NPD/YAK-203/BCP system have been experimentally investigated in a wide range of the measurement conditions. It is shown that at voltages corresponding to the effective radiative recombination of charge carriers, a significant decrease in the differential capacitance of the structures is observed. The frequency dependences of the normalized conductance of LED structures are in good agreement with the results of numerical simulation in the framework of the equivalent circuit method. Changes in the frequency dependences of the admittance with a change in temperature are most pronounced in the temperature range of 200–300 K and less noticeable in the temperature range of 8–200 K. From the frequency dependences of the imaginary part of impedance, the charge carrier mobilities are found at various voltages and temperatures. The mobility values obtained by this method are somewhat lower than those determined by the transient electroluminescence method. The dependence of the mobility on the electric field is well approximated by a linear function. As the temperature decreases from 300 to 220 K, the mobility decreases several times.
关键词： frequency dependence of imaginary part of impedance,LED structure,current-voltage characteristic,transient electroluminescence,organic semiconductor,charge carrier mobility,method of equivalent circuits,admittance
更新于2025-11-14 17:28:48
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Effect of K2O addition on glass structure, complex impedance and energy storage density of NaNbO3 based glass-ceramics
摘要： (40-x)Na2O-xK2O-40Nb2O5-20SiO2 (x=0, 5, 10, 15mol%) glass-ceramics are synthesized by traditional melts method. The glass-ceramics are tested by X-ray diffraction (XRD) techniques, and NaNbO3 as major phase led a high permittivity. A microstructure with nanoscale grains enclosed by glass phase is observed by scanning electron microscope (SEM). With the increase of content of K2O, a relaxed glass network structure is obtained, and more kinds of phase are formed. Permittivity comes to 174 approximately when x=5mol%. In addition, the activation energy (Ea) of residual glass phase for Na2O-K2O-Nb2O5-SiO2 glass-ceramics firstly increase then decrease. Breakdown strength (BDS) of all samples increase and then decrease with the increase of content of K2O, and maximum BDS is obtained when x=10mol%. And maximum theoretical energy density is 1.43J/cm3 when x=5mol%.
关键词： breakdown strength,glass network structure,Na2O-K2O-Nb2O5-SiO2 glass-ceramics
更新于2025-11-14 17:28:48
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Electrical characterization of high k-dielectrics for 4H-SiC MIS devices
摘要： We report promising results regarding the possible use of AlN or Al2O3 as a gate dielectric in 4H-SiC MISFETs. The crystalline AlN ?lms are grown by hot wall metal organic chemical vapor deposition (MOCVD) at 1100 °C. The amorphous Al2O3 ?lms are grown by repeated deposition and subsequent low temperature (200 °C) oxidation of thin Al layers using a hot plate. Our investigation shows a very low density of interface traps at the AlN/4H-SiC and the Al2O3/4H-SiC interface estimated from capacitance-voltage (CV) analysis of MIS capacitors. Current-voltage (IV) analysis shows that the breakdown electric ?eld across the AlN or Al2O3 is ～ 3 MV/cm or ～ 5 MV/cm respectively. By depositing an additional SiO2 layer by plasma enhanced chemical vapor deposition at 300 °C on top of the AlN or Al2O3 layers, it is possible to increase the breakdown voltage of the MIS capacitors signi?cantly without having pronounced impact on the quality of the AlN/SiC or Al2O3/SiC interfaces.
关键词： MIS structure,Interface traps,Al2O3/4H-SiC interface,AlN/4H-SiC interface
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
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Conductive electrodes based on Ni–graphite core–shell nanoparticles for heterojunction solar cells
摘要： Ni–graphite core–shell nanoparticles (CSNPs), which consisted of Ni nanoparticles (NPs) wrapped with several graphene layers, were grown by the thermal reduction of NiO NPs using H2. The effect of the synthesis temperature (800, 900, 1000, and 1100 °C) on the formation of multilayer graphene shells on the Ni core NPs was investigated to evaluate the structural and electrical characteristics of the particles. The proposed chemical reactions for the formation of Ni NPs can be summarized as follows: formation of liquid Ni by the reduction of NiO, thermal decomposition of the NiO phase, and formation of multilayer graphene shell because of the supersaturation of C in the liquid Ni phase. The resistivity of the electrode pattern fabricated with the Ni–graphite CSNP paste was found to be 6.75 × 10?3 ?·cm. Further, the power conversion efficiency of bulk heterojunction solar cells fabricated with the Ni–graphite CSNPs is higher than that of cells fabricated without the Ni- graphite CSNPs. Thus, our Ni–graphite CSNPs can be employed as a highly efficient electrode material in bulk heterojunction solar cells.
关键词： Thermal reduction,Core–shell structure,Nickel oxide nanoparticle,Graphite,Graphene
更新于2025-11-14 17:04:02