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XPS and thermal studies of silver doped SiO2 matrices for plasmonic applications
摘要： Silver nanocrystals doped SiO2 matrices were synthesized through sol–gel route using acid catalyst. The prepared silica matrices with different concentrations of silver were annealed at different temperatures and characterized using, XRD, FTIR, Absorption spectroscopy, XPS, thermogravimetric and differential thermal analysis. The XRD data con?rm the amorphous nature of silica and crystalline nature of silver nanocrystals. Using the Fourier-transform infrared red spectrum the formation of silica glass was con-?rmed. The characteristic Surface Plasmon Resonance of silver nanoparticles obtained around 400 nm from the absorption spectrum. The observed blue shift and skewness in SPR with increasing silver con-centrations were studied. The 3d doublet state of silver at a binding energy of 368.4 eV with the splitting of 6 eV obtained in XPS con?rm the state Ag0 along with the presence of a minor quantity of silver (II) oxide. The thermal stability and nature were analyzed using TGA-DTG and DTA and showed good thermal stability from 400 (cid:1)C to higher temperatures.
关键词： Sol-gel,Surface plasmon resonance,Thermal analysis,XPS,Silver nanocrystals
更新于2025-09-23 15:19:57
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Surface Ligands Management for Efficient CsPbBrI <sub/>2</sub> Perovskite Nanocrystal Solar Cells
摘要： CsPbX3 (X= Cl, Br, I) inorganic perovskite nanocrystals (PNCs) not only maintain the excellent optical and electronic properties of bulk material but also possess the features of nano-materials, such as tunable bandgap, easily processable colloidal ink, enable them to be suitable for incorporation into various electronic devices and compatible with printing techniques. In contrast to the traditional II-VI and III-V semiconductor nanocrystals, the unique defect-tolerance effect makes the CsPbX3 PNCs very promising materials for optoelectronic applications. The ligands around the NCs play a critical role on the optoelectronic devices performance. Here, through a facile hexane/ethyl acetate (MeOAc) solvent treatment method to control the ligand amount around the CsPbBrI2 PNCs, we systematically demonstrated the impact of ligand amount on the performance of solar cell devices and first quantify the ligand amount precisely by nuclear magnetic resonance (NMR) internal standard method. Through controlling the ligand amount, the film quality, charge transfer and transport properties are largely improved. In addition, a simple annealing process is applied to improve the interface properties by partial crystal fusion. As a consequence, the photovoltaic power conversion efficiency (PCE) of 12.2% is achieved by employing a n-i-p device structure, which is the highest performance of mixed-halide CsPbX3 NCs solar cells. This work emphasizes the important role of ligand amount on the NCs device performance.
关键词： ligand amount control,CsPbBrI2,solar cell,inorganic perovskite,nanocrystals
更新于2025-09-23 15:19:57
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Ammonium acetate passivated CsPbI3 perovskite nanocrystals for efficient red light-emitting diodes
摘要： Lead halide perovskite nanocrystals (PNCs) have very recently emerged as promising emitters for their superior optoelectronic properties. However, the defects in perovskite itself make it susceptible to the external environment and internal ion migration, resulting in low photoluminescence quantum yield (PLQY) and poor device efficiency. Herein, we developed a method to reduce the surface defects of PNCs by introducing ammonium acetate in the synthesis of CsPbI3 PNCs. The addition of ammonium acetate can effectively eliminate undesired surface metallic lead cations and dangling bonds, resulting in an enhanced PLQY and stability. The passivated PNCs have an overall up-shift energy level, demonstrating better hole injection efficiency. As a result, the red light-emitting diodes (LEDs) fabricated with the passivated CsPbI3 PNCs achieved an optimal EQE of 10.6% and a maximum brightness of 981 cd/m2, which are 3.1 and 2.4 times that of unpassivated PNCs based devices, respectively.
关键词： CsPbI3 nanocrystals,ammonium acetate,defect passivation,photoluminescence quantum yield,light-emitting diodes
更新于2025-09-23 15:19:57
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Stabilizing the Plasmonic Response of Titanium Nitride Nanocrystals with a Silicon Oxynitride Shell: Implications for Refractory Optical Materials
摘要： We discuss the synthesis and properties of nanoparticles and thin films for refractory plasmonic applications. The approach focuses on titanium nitride (TiN), which overcomes the limitations of more common plasmonic materials like silver and gold with respect of temperature stability. Free-standing TiN-based nanoparticles are produced in two serially connected plasma reactors, where TiN nanocrystals are nucleated in a first plasma stage, then aerodynamically dragged in a second stage and conformally coated with a silicon nitride layer. An in-depth comparison between bare and coated TiN nanoparticles is presented in terms of the structural, chemical and optical properties. Coating of the titanium nitride core reduces its oxidation upon exposure to air, drastically improving plasmonic response. Thin films realized using the core-shell structure show practically no change in reflectivity even when the thin films are heated to 900°C in an inert atmosphere. This study introduces a simple surface passivation schemes that enhances the functionality of the material, providing further confirmation of the potential of nitride-based plasmonic material as high-quality refractory optical compounds for a broad range of applications.
关键词： Titanium nitride,Non-thermal plasma,Thin films,Nanocrystals,Refractory nanomaterials,Plasmonic nanomaterials
更新于2025-09-23 15:19:57
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Properties, fabrication and applications of plasmonic semiconductor nanocrystals
摘要： In semiconductor nanocrystals (NCs), a new regime has been opened in the plasmonic field since the discovery of localized surface plasmon resonances (LSPRs). LSPRs that lead to near-field enhancement, scattering, and resonant absorption around the NC can be tuned in the range from the visible to the near-infrared (NIR) region across a wide optical spectrum by synthetically varying the doping level, and post synthetically via electrochemical control, photochemical control, and chemical oxidation and reduction. In this review, we will focus on the three widely explored and interrelated examples and their manipulation methods of LSPR of (1) hydrogen molybdenum bronze (HxMoO3?y) NCs, (2) hydrogen tungsten bronze (HxWO3?y) NCs, and (3) oxygen vacancy doped molybdenum tungsten oxide (MoxW1?xO3?y) NCs. Finally, a brief outlook on the applications of these plasmonic NCs is presented.
关键词： hydrogen molybdenum bronze,localized surface plasmon resonances,hydrogen tungsten bronze,plasmonic semiconductor nanocrystals,molybdenum tungsten oxide
更新于2025-09-23 15:19:57
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Electrochemical Switching of Plasmonic Colors Based on Polyaniline-Coated Plasmonic Nanocrystals
摘要： Plasmonic color generation has attracted much research interest due to the unique optical properties of plasmonic nanocrystals that are promising for chromatic applications, such as flat-panel displays, smart windows and wearable devices. Low-cost, monodisperse plasmonic nanocrystals supporting strong localized surface plasmon resonances are favorable for the generation of plasmonic colors. However, many implementations so far have either a single static state or complexities in the particle alignment and switching mechanism for generating multiple displaying states. Herein we report on a facile and robust approach for realizing the electrochemical switching of plasmonic colors out of colloidal plasmonic nanocrystals. The metal nanocrystals are coated with a layer of polyaniline, whose refractive index and optical absorption are reversibly switched through the variation of an applied electrochemical potential. The change in the refractive index and optical absorption results in the modulation of the plasmonic scattering intensity with a depth of 11 dB. The electrochemical switching process is fast (~5 ms) and stable (over 1000 switching cycles). A device configuration is further demonstrated for switching plasmonic color patterns in a transparent electrochemical device, which is made from indium-tin-oxide electrodes and a polyvinyl alcohol solid electrolyte. Our control of plasmonic colors provides a favorable platform for engineering low-cost and high-performance miniaturized optical devices.
关键词： polyaniline,electrochemical switching,plasmonic color display,noble metal nanocrystals,plasmonic colors,plasmon resonance
更新于2025-09-23 15:19:57
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Controllable synthesis of all inorganic lead halide perovskite nanocrystals and white light-emitting diodes based on CsPbBr3 nanocrystals
摘要： The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated in this article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.
关键词： Cesium lead halide perovskite,white light-emitting diodes,photoluminescent,hot-injection method,nanocrystals
更新于2025-09-23 15:19:57
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Enhancement of Photoluminescence Quantum Yield and Stability in CsPbBr3 Perovskite Quantum Dots by Trivalent Doping
摘要： We determine the influence of substitutional defects on perovskite quantum dots through experimental and theoretical investigations. Substitutional defects were introduced by trivalent dopants (In, Sb, and Bi) in CsPbBr3 by ligand-assisted reprecipitation. We show that the photoluminescence (PL) emission peak shifts toward shorter wavelengths when doping concentrations are increased. Trivalent metal-doped CsPbBr3 enhanced the PL quantum yield (~10%) and air stability (over 10 days). Our findings provide new insights into the influence of substitutional defects on substituted CsPbBr3 that underpin their physical properties.
关键词： ligand-assisted reprecipitation,trivalent doping,nanocrystals,perovskite,CsPbBr3
更新于2025-09-23 15:19:57
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Nanoshell quantum dots: Quantum confinement beyond the exciton Bohr radius
摘要： Nanoshell quantum dots (QDs) represent a novel class of colloidal semiconductor nanocrystals (NCs), which supports tunable optoelectronic properties over the extended range of particle sizes. Traditionally, the ability to control the bandgap of colloidal semiconductor NCs is limited to small-size nanostructures, where photoinduced charges are confined by Coulomb interactions. A notorious drawback of such a restricted size range concerns the fact that assemblies of smaller nanoparticles tend to exhibit a greater density of interfacial and surface defects. This presents a potential problem for device applications of semiconductor NCs where the charge transport across nanoparticle films is important, as in the case of solar cells, field-effect transistors, and photoelectrochemical devices. The morphology of nanoshell QDs addresses this issue by enabling the quantum-confinement in the shell layer, where two-dimensional excitons can exist, regardless of the total particle size. Such a geometry exhibits one of the lowest surface-to-volume ratios among existing QD architectures and, therefore, could potentially lead to improved charge-transport and multi-exciton characteristics. The expected benefits of the nanoshell architecture were recently demonstrated by a number of reports on the CdSbulk/CdSe nanoshell model system, showing an improved photoconductivity of solids and increased lifetime of multi-exciton populations. Along these lines, this perspective will summarize the recent work on CdSbulk/CdSe nanoshell colloids and discuss the possibility of employing other nanoshell semiconductor combinations in light-harvesting and lasing applications.
关键词： Optoelectronic properties,Nanoshell quantum dots,CdSbulk/CdSe nanoshell,Colloidal semiconductor nanocrystals,Quantum confinement
更新于2025-09-23 15:19:57
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Top-down Fabrication of Colloidal Plasmonic MoO <sub/>3-x</sub> Nanocrystals via Solution Chemistry Hydrogenation
摘要： A high-efficiency top-down approach was used to fabricate orthorhombic MoO3-x nanocrystals through the synergic effect of oleic acid (OA) and oleylamine (OAm), in which OA providing H+ ions and OAm contributing free electrons. This investigation might provide new guidance for manipulating the optical properties of metal oxide semiconductors.
关键词： top-down fabrication,solution chemistry hydrogenation,oleic acid,oleylamine,colloidal plasmonic MoO3-x nanocrystals
更新于2025-09-23 15:19:57