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First-principles study on photovoltaic properties of 2D Cs <sub/>2</sub> PbI <sub/>4</sub> -black phosphorus heterojunctions
摘要： Both 2D perovskite Cs2PbI4 and phosphorus are significant optoelectronic semiconductor materials, the optical-electrical characters between both contact interfaces are interesting topics. In present work, we demonstrate comparative investigation of optoelectronic properties for two kinds of electrical contact interfaces. i.e. Pb–I and Cs–I interfaces with black phosphorus contacts. The carrier transport, charge transferring and optical properties for both cases are investigated by using first principle calculation. Both contact interfaces exhibit type II band alignment with direct band gap. Charge carrier migration from Cs–I interface to black phosphorus is more strong than that of Pb–I interface by considering differential charge density and bader charge between distinct electrical contact interfaces. Besides, electron–hole effective masses of heterojunctions for both cases along different direction are investigated. Optical absorption coefficients of both cases are compared with those of free-standing Cs2PbI4 and black phosphorus in the visible spectrum. We systematically compared advantages and disadvantages of two kinds of contact interfaces for photovoltaic application, and the results reveal interfacial engineering of 2D heterojunction plays a important role in tuning optoelectronic properties.
关键词： optical property,first-principles,electronic structures,2D heterojunction,carrier effective masses,charge transfer
更新于2025-09-23 15:19:57
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CuInS <sub/>2</sub> -Doped ZnS Quantum Dots Obtained via Non-Injection Cation Exchange Show Reduced but Heterogeneous Blinking and Provide Insights into Their Structurea??Optical Property Relationships
摘要： Cadmium-free CuInS2-doped ZnS quantum dots (QDs) are synthesized through a 2-step non-injection synthetic method. The resulting QDs are small (8 nm or less) and relatively isotropic with photoluminescence quantum yields (PL QY) up to almost 70% and emission peaks in the 560-600 nm window, depending on the amount of Zn precursor added. The results indicate small CuInS2 ‘clusters’ within a zinc-blende ZnS lattice are the radiative recombination centers in the nanoparticle. Interestingly, higher ensemble photoluminescence quantum yields (PL QY) result when cation exchange is less extensive (~80 % ZnS composition), while a reduction in blinking is observed when ZnS composition exceeds 99%. A wide heterogeneity in blinking behavior from QD-to-QD is evident and a subpopulation statistical analysis shows that the on-state dwell times change from multiexponential (or inverse power law) behavior towards more mono-exponential behavior for particles that spend more of their time in the on-state. These results indicate that, as the number of CuInS2 emitting centers is reduced, the number of pathways leading to the off-state decreases, and a model is proposed to relate this behavior to the QD structure. These results provide a novel route towards CuInS2-doped visible-light emitting ZnS QDs with high quantum yield and reduced blinking and provides insight into how the composition of dopant and host matrix affects the radiative recombination mechanisms in single particles.
关键词： non-injection cation exchange,CuInS2-doped ZnS,blinking,structure-optical property relationships,quantum dots
更新于2025-09-23 15:19:57
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Mechanically Robust and Broadband Blackbody Composite Films Based on Self-Assembled Layered Structures
摘要： Inspired by nacre that is mechanically strong and versatile in light manipulation, large-scale black films with a nacre-like microstructure and carbon nanotubes inclusion were prepared using a facile self-assembly technique. Layered structure promoted blackness and toughness were simultaneously realized, affording robust films with solar–absorptivity as high as 96.9%. Our design strategy and fabrication process will be beneficial for the facile access to various advanced blackbody coatings.
关键词： vacuum-assisted self-assembly,layered structure,mechanical property,blackbody,polymer nanocomposite
更新于2025-09-23 15:19:57
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Synergetic adsorption and photo-Fenton degradation of methylene blue by ZnFe <sub/>2</sub> O <sub/>4</sub> /SiO <sub/>2</sub> magnetic double-mesoporous-shelled hollow spheres
摘要： Adsorption and Fenton technologies have been widely employed to deal with wastewater. ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres (MDSHSs) were feasibly synthesized by a solvothermal method. The as-synthesized MDSHSs show excellent adsorption and selectivity for methylene blue (MB), which it took about only 1 min to reach the adsorption equilibrium. About 50% MB was removed by adsorption, and other 50% MB was degraded under further photo-Fenton process. Effects of experimental conditions on the adsorption and photo-Fenton process were investigated. The mechanisms of MDSHSs formation and photo-Fenton process were proposed. Total organic carbon (TOC) reduction reached as high as 90% with 60 mg/L of MB for 90 min. The experimental results indicated that MDSHSs exhibit a remarkable adsorption and catalytic activity for photo-Fenton process in a wide pH range of 3.3–11.0. Simultaneously, the composite shows an excellent stability and reusability.
关键词： photo-Fenton,magnetic property,porous materials,ZnFe2O4/SiO2,adsorption
更新于2025-09-23 15:19:57
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Recent development of soluble hole injection material for OLED display
摘要： We developed soluble hole injection materials and inks, named ELsource, that can be used as hole injection layer in organic light-emitting diode (OLED) display. OLED is an optical device. Therefore, we developed the hole injection materials with optical properties necessary for an optical device.
关键词： refractive index,optical property,printable OLED,flexible,HIL,hole injection layer,soluble,hole injection material,adhesion,HIM
更新于2025-09-23 15:19:57
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Study of nanometer-scale structures and electrostatic properties of InAs quantum dots decorating GaAs/AlAs core/shell nanowires
摘要： The configurations of core/shell nanowires (NWs) and quantum dots (QDs) decorating NWs have found great applications in forming optoelectronic devices thanks to their superior performances, and the combination of the two configurations would expect to bring more benefits. However, the nanometer-scale electrostatic properties of the QD/buffer layer/NW heterostructures are still un-revealed. In this study, the InAs QDs decorating GaAs/AlAs core/shell NWs are systemically studied both experimentally and theoretically. The layered atomic structures, chemical information, and anisotropic strain conditions are characterized by comprehensive transmission electron microscopy (TEM) techniques. Quantitative electron holography analyses show large number of electrons accumulating in the InAs QD especially at the dot apex, and charges of reversed signs and similar densities are observed to distribute at the sequential interfaces, leaving great amount of holes in the NW core. Theoretical calculations including simulated heterostructural band structures, interfacial charge transfer, and chemical bonding analysis are in good accordance with the experimental results, and prove the important role of AlAs buffer layer in adjusting the heterostructural band structure as well as forming stable InAs QDs on the NW surfaces. These results could be significant for achieving related optoelectronic devices with better stability and higher efficiency.
关键词： quantum dot,transmission electron microscopy,atomic structure,core/shell nanowire,electrostatic property
更新于2025-09-23 15:19:57
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An insight into microstructural heterogeneities formation between weld subregions of laser welded copper to stainless steel joints
摘要： The effect of laser beam welding (LBW) process on the microstructure?mechanical property relationship of a dissimilar weld between the copper (Cu) and stainless steel (SS) was investigated. Backscattered electron (BSE) based scanning electron microscopy (SEM) imaging was used to characterize the highly heterogeneous microstructural features across the LBW (Cu?SS) weld. The BSE analysis thoroughly evidenced the complex microstructures produced at dissimilar weld interfaces and fusion zone along with the compositional information. Widely different grain growths from coarse columnar grains to equiaxed ultrafine grains were also evident along the Cu?weld interface. A high-resolution electron backscattered diffraction (EBSD) analysis confirmed the existence of the grain refinement mechanism at the Cu?weld interface. Both tensile and impact properties of the dissimilar weld were found to be closely aligned with the property of Cu base metal. Microhardness gradients were spatially evident in the non-homogeneous material composition zones such as fusion zone and the Cu?weld interface regions. The heterogeneous nucleation spots across the weld sub-regions were clearly identified and interlinked with their microhardness measurements for a holistic understanding of structure?property relationships of the local weld sub-regions. The findings were effectively correlated to achieve an insight into the local microstructural gradients across the weld.
关键词： impact toughness,laser beam welding,stainless steel,microstructural characterization,copper,tensile property
更新于2025-09-23 15:19:57
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Comparison of nonclassical properties resulting from non-Gaussian operations
摘要： Based on an asymmetrical beam splitter (ABS) and conditional measurement, we have investigated the nonclassical properties of non-Gaussian states in a unified form, including photon subtraction, photon addition and quantum catalysis, by deriving analytical expressions for photon number, squeezing effect, Mandel Q parameter and Wigner function. It is found that these properties not only depend on squeezing parameter and measurement, but also on the transmissivity of the ABS. Photon addition and quantum catalysis present a higher probability in the regions of low and high transmissivity, respectively. Although both single-photon subtraction and addition share a clear negative volume, the latter is considered to be a better choice for producing nonclassical states than the two others, if both success probability and negative volume in the small squeezing region are taken into consideration. Quantum catalysis is better in the large squeezing region and with low transmissivity. These results provide some reference for generating such non-Gaussian states.
关键词： success probability,squeezed vacuum,nonclassical property,Hermite polynomials excitation
更新于2025-09-23 15:19:57
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The antibacterial effect of potassium-sodium niobate ceramics based on controlling piezoelectric properties
摘要： The implant infection is one of the most serious postsurgical complications of medical device implantation. Therefore, the development of biocompatible materials with improved antibacterial properties is of great importance. It might be a new insight to apply the intrinsic electrical properties of biomaterials to solve this problem. Here, potassium-sodium niobate piezoceramics (K0.5Na0.5NbO3, KNN) with different piezoelectric constants were prepared, and the microstructures and piezoelectric properties of these piezoceramics were evaluated. Moreover, the antibacterial effect and biocompatibility of these piezoceramics were assayed. Results showed that these piezoceramics were able to decrease the colonies of bacteria staphylococcus aureus (S. aureus), favor the rat bone marrow mesenchymal stem cells (rBMSCs) proliferation and promote the cell adhesion and spreading. The above effects were found closely related to the surface positive charges of the piezoceramics, and the sample bearing the most positive charges on its surface (sample 80KNN) had the best performance in both antibacterial effect and biocompatibility. Based on our work, it is feasible to develop biocompatible antibacterial materials by controlling piezoelectric properties.
关键词： Positive charges,Biocompatibility,Potassium-sodium niobate,Antibacterial property
更新于2025-09-23 15:19:57
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Nonlinear optical and optical power limiting studies of Zn1-xMnxO thin films prepared by spray pyrolysis
摘要： Zn1-xMnxO (x=0, 0.02, 0.04, 0.06, 0.08 and 0.1) thin films were deposited at 723 K temperature on glass substrate using a solution of molarity of 0.0125M through spray pyrolysis method. X-ray diffractogram (XRD) analysis confirmed that all the films have (0 0 2) as a preferential orientation with hexagonal wurtzite structure. The increase of dopant marginally changed the crystallite size and lattice parameters. Surface morphology changes fibrous to spherical structure with an increase in doping. X-ray photoelectron spectroscope (XPS) measurements proved the occurrence of manganese is in the Mn2+ transition state along with Oxygen and Zinc content. The films showed ~90-80% transmittance in the visible region with increasing in Mn concentration. The energy band-gap reduced with increase in dopant, due to sp-d exchange interactions. The nonlinear optical (NLO) properties were studied using z-scan technique under continuous wave (CW) diode pumped solid-state (DPSS) laser operating at 532 nm wavelength. Reverse saturable absorption (RSA) behaviors observed in both undoped and Mn doped films which is attributed to two-photon absorption (TPA) process. The optical limiting properties were also studied, which suggests that the prepared thin films could be used as optical limiters in the visible region.
关键词： ZnMnO films,structural property,nonlinear optical properties,optical property
更新于2025-09-19 17:15:36