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On-Demand Electromagnetic Hotspot Generation in Surface Enhanced Raman Scattering Substrates via “Add-On” Plasmonic Patch
摘要： Electromagnetic hotspots at the interstices of plasmonic assemblies are recognized to be the most potent sites for surface enhanced Raman scattering (SERS). We demonstrate a novel “add-on” electromagnetic hotspot formation technique, which significantly improves the sensitivity of conventional SERS substrates comprised of individual plasmonic nanostructures. The novel approach demonstrated here involves the transfer of “plasmonic patch”, a transparent, flexible and conformal elastomeric film adsorbed with plasmonic nanostructures, onto a conventional SERS substrate. The addition of plasmonic patch onto conventional SERS substrate following the analyte capture results in the formation of electromagnetic hotspots and hence large SERS enhancement. The application of plasmonic patch improves the sensitivity and limit of detection of conventional SERS substrates by upto ~100-fold. The transfer of plasmonic patch also effectively transforms the SERS-inactive gold mirror to a highly SERS-active “particle-on-mirror” system. Furthermore, we demonstrate that the “add-on” technique can be effectively utilized for the vapor phase detection of explosives such as trinitrotoluene (TNT) using peptide recognition elements. We believe that the on-demand hotspot formation approach presented here represents a highly versatile and ubiquitously applicable technology readily expandable to any existing SERS substrate without employing complicated modification.
关键词： Trinitrotoluene (TNT),On-Demand Electromagnetic Hotspots,Surface Enhanced Raman Scattering (SERS),Plasmonic Patch,Plasmonic Nanostructures
更新于2025-09-11 14:15:04
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3D, covalent and noncovalent hybrid materials based on 3-phenylcoumarin derivatives and single walled carbon nanotubes as gas sensing layers
摘要： In this work, the effect of different types of functionalization of single walled carbon nanotubes (SWCNT) with 3-phenylcoumarin derivatives on the chemiresistive sensor response to ammonia (10–50 ppm) was studied. Covalent functionalization of SWCNT was performed according to the Huisgen reaction of azide-alkyne 1,3-dipolar cycloaddition between mono alkyne-substituted 3-phenylcoumarin and single walled nanotubes modified by azide groups. Covalent functionalization was shown by IR- and X-ray photoelectron spectroscopy. To obtain the 3D hybrid material, the dialkyne functionalized 3-phenylcoumarin molecules were used as linkers between nanotubes. Third hybrid material was prepared by noncovalent functionalization of SWCNT, namely by adsorption of 7-propinyloxy-3-(p-propinyloxyphenyl)coumarin on SWCNT surface. It was shown that the 3D hybrid and the hybrid obtained by covalent functionalization exhibit 2 and 4 times higher sensor responses to ammonia compared to noncovalently functionalized SWCNT. The value of sensor response is in good correlation with the degree of functionalization of SWCNTs with coumarin molecules.
关键词： Non covalent functionalization,3D carbon nanostructures,Covalent functionalization,Carbon nanomaterials,Ammonia sensor,Coumarin
更新于2025-09-11 14:15:04
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Design and Optimization of Nanostructured UV-Filters for Efficient and Stable Perovskite Solar Cells
摘要： The Design and optimization of a nanostructured UV-light filters, for perovskite solar cells, significantly improves the stability of perovskite solar cells in the UV-light region, where the UV-severe instability issues found in the degradation of perovskite materials under UV-light by using COMSOL Multiphysics commercial package is performed. This design is crucial for under a 50 nm bi-composite layer of TiO2 and WO3 nanoparticles. The proposed structure of TiO2, WO3, and ZnO. It is noted that the most efficient structure is a 10 nm TiO2 thin film illumination. The suggested structure is a thin film of TiO2 in conjunction with nanoparticles layers blocking properties are enhanced by about 75% compared with the solar cell without using the suggested filter design.
关键词： modeling,UV-light filter,stability of perovskite solar cells,nanostructures,Perovskite solar cells
更新于2025-09-11 14:15:04
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Ultrathin Polymer Nanofibrils for Solar-Blind Deep Ultraviolet Light Photodetectors Application
摘要： Solar-blind deep ultraviolet photodetectors (DUVPDs) based on conventional inorganic ultrawide bandgap semiconductors (UWBS) have shown promising application in various civil and military fields and yet they can hardly be used in wearable optoelectronic devices and systems for lack of mechanical flexibility. In this study, we report a non-UWBS solar-blind DUVPD by designing ultrathin polymer nanofibrils with a virtual ultrawide bandgap, which was obtained by grafting P3HT with PHA via a polymerization process. Optoelectronic analysis reveals that the P3HT-b-PHA nanofibrils are sensitive to DUV light with a wavelength of 254 nm but are virtually blind to both 365 nm and other visible light illuminations. The responsivity is 120 A/W with an external quantum efficiency of up to 49700%, implying a large photoconductive gain in the photoresponse process. The observed solar-blind DUV photoresponse is associated with the resonant mode due to the leakage mode of the ultrathin polymer nanofibrils. Moreover, a flexible image sensor composed of 10 × 10 pixels can also be fabricated to illustrate their capability for image sensing application. These results signify that the present ultrathin P3HT-b-PHA nanofibrils are promising building blocks for assembly of low-cost, flexible, and high-performance solar-blind DUVPDs.
关键词： image sensor,leakage mode,Optoelectronic device,polymer nanostructures,virtual ultrawide bandgap semiconductor
更新于2025-09-11 14:15:04
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Highly Plasmonic Titanium Nitride by Room-Temperature Sputtering
摘要： Titanium nitride (TiN) has recently emerged as an attractive alternative material for plasmonics. However, the typical high-temperature deposition of plasmonic TiN using either sputtering or atomic layer deposition has greatly limited its potential applications and prevented its integration into existing CMOS device architectures. Here, we demonstrate highly plasmonic TiN thin films and nanostructures by a room-temperature, low-power, and bias-free reactive sputtering process. We investigate the optical properties of the TiN films and their dependence on the sputtering conditions and substrate materials. We find that our TiN possesses one of the largest negative values of the real part of the dielectric function as compared to all other plasmonic TiN films reported to date. Two-dimensional periodic arrays of TiN nanodisks are then fabricated, from which we validate that strong plasmonic resonances are supported. Our room-temperature deposition process can allow for fabricating complex plasmonic TiN nanostructures and be integrated into the fabrication of existing CMOS-based photonic devices to enhance their performance and functionalities.
关键词： room-temperature sputtering,optical properties,nanostructures,Titanium nitride,plasmonics
更新于2025-09-11 14:15:04
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Synthesis of Plasmonic Photonic Crystal SiO2–Ag Nanostructures by Ion Beam Deposition of Silver Clusters onto Silica Microspheres
摘要： The synthesis of plasmonic photonic crystal SiO2–Ag nanostructures by deposition of silver nanoparticles is considered. The technique includes the physical sputtering of a silver target with a kiloelectronvolt argon ion beam onto silica microspheres obtained according to St?ber. The plasmon resonance effect is shown to be interrelated with the optical properties of nanostructured supports and the morphology of aggregate structures of silver nanoparticles (clusters).
关键词： silica microspheres,ion beam deposition,plasmonic photonic crystal,SiO2–Ag nanostructures,silver clusters
更新于2025-09-11 14:15:04
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pH-Dependent Degradation of Layered Black Phosphorus: Essential Role of Hydroxide Ions
摘要： The practical application of layered black phosphorus (LBP) was challenged by fast decomposition in the presence of H2O and/or O2, and the role of H2O was highly controversial. Herein, we proposed a hydroxide ion (OH-)-initiated degradation mechanism for LBP to elucidate the role of H2O. We found that LBP degraded faster in alkaline solutions than in neutral or acidic solutions with or without O2. Degradation rates of LBP increased linearly from pH 4 to 10. Density functional theory calculations showed that OH- initiated the decomposition of LBP through breaking the P–P bond and forming a P–O bond. The detection of hypophosphite, generated from OH- reacting with P atoms, confirmed the hypothesis. Protons acted in a way distinctive from OH-, by inducing deposition/aggregation or forming a cation-π layer to protect LBP from degradation. This work revealed the exact degradation mechanism of LBP to facilitate the development of effective stabilization technologies.
关键词： Degradation mechanism,Hydroxide ion,Nanostructures,Density functional calculations,Black phosphorus
更新于2025-09-10 09:29:36
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Tuning and enhancing the red upconversion emission of Er3+ in LiYF4 nanoparticles
摘要： The tetragonal-phased LiYF4:Yb3+/Er3+ nanoparticles with different core-shell nanostructures have been successfully synthesized by a modified solution-based method. The upconversion emissions of LiYF4: Yb3+/Er3+ nanoparticles were precisely tuned from green to red with the increase in Yb3+ concentrations under 980 nm excitation. The corresponding intensity ratios of the red and green emissions (R/G ratios) were enhanced from 0.06 to 5.33. However, the overall integral upconversion intensity of LiYF4:Yb3+/Er3+ nanoparticles clearly decreased when the Yb3+ doping concentrations were increased. For the enhancement of the red upconversion intensity and expansion of their application, two kinds of core-shell nanostructures, namely, LiYbF4:Er3+@LiYF4 and LiYbF4:Er3+@LiYbF4, were constructed through epitaxial growth at similar experimental conditions. The LiYbF4:Er3+@LiYF4 core-shell nanostructures exhibited stronger upconversion emission and higher R/G ratios than the LiYbF4:Er3+ and LiYbF4:Er3+@LiYbF4 nanoparticles. The highest R/G ratios increased to 6.27 in LiYbF4:Er3+@LiYF4 core-shell nanostructures, increasing 104-fold. The upconversion regulation and enhancing mechanism were also discussed according to the emission spectra and fluorescence lifetimes.
关键词： upconversion,LiYF4 nanoparticles,core/shell nanostructures,cross relaxation
更新于2025-09-10 09:29:36
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A study of 8 MeV e-beam on localized defect states in ZnO nanostructures and its role on Photoluminescence and third harmonic generation
摘要： In this article we have explored an effect of electron beam irradiation (EBI) on physical and nonlinear optical properties ZnO thin nano films. Nanostructured ZnO thin films were grown by low cost spray pyrolysis technique. The irradiation dosage has been fixed at 5kGy, 10kGY, 15kGy and 20kGy. The structural investigation by Glancing angle X-Ray Diffractometer (GAXRD) confirms a polycrystalline phase of ZnO with wurtzite structure. The variation in the surface morphology upon EBI has been demonstrated using 2D and 3D Atomic force microscopy (AFM) images. Nanoscope software analysis quantifies the variation in surface roughness and average particle height upon EBI. The defect states created in the films upon irradiation experiments were investigated using UV- visible spectrophotometer, Room temperature Photoluminescence (RTPL), Raman and X-ray photoelectron spectroscopy (XPS). The increase in urbach tail validates the creation of localized defect states in the films The Gaussian fitting on RTPL spectra shows the quenching in the luminescent centers upon irradiation arised as result of recombination of vacancy defects. Phonon confinement model fitting on Raman spectra endorses that shift in the phonon modes observed on irradiation is due to spatial confinement of phonons. The elemental composition and impurity states of the EBI ZnO thin films were studied using XPS spectra. The shift in the binding energy of Zn and O elements infers the electron beam induced changes in the films. The electron beam irradiation has resulted in the increment of third order optical susceptibility χ(3) from 3.5×10-4esu to 8.13×10-3esu due to the enhancement of electronic transition to different defect levels formed in the films and through local heating effects arising due to continuous wave (CW) laser illumination. The enhanced THG signal investigated using Nd:YAG laser at 1064nm and 8 ns pulse width shows the promising features of EBI ZnO films for frequency tripling applications.
关键词： Electron beam irradiation,Phonon confinement model,third harmonic generation,ZnO nanostructures,Localized defect states
更新于2025-09-10 09:29:36
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Effect of the zinc salt concentration on the ZnO thin films properties grown by MWCBD
摘要： Nanostructured ZnO thin films with different surface morphologies have been synthesized by the microwave assisted chemical bath deposition technique (MWCBD), adjusting the pH of the reaction solution between 9 and 11.14. Newest results are presented in this work supported by previous investigations. Morphology, structure and optical properties of the films have been studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and room temperature photoluminescence (PL) techniques. It has been observed that the zinc salt concentration and the pH of the reaction solution determines the reaction kinetics, affecting strongly the morphology of the final product. However, the rapid heating in microwave irradiation process facilitates the crystallization of the formed nano-/microstructures. Effects of composition and morphology of the grown nano-/microstructures on their photoluminescence (PL) behaviors have been discussed.
关键词： Optical properties,Microwave deposition,ZnO nanostructures,Morphology control
更新于2025-09-10 09:29:36