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Tailoring a Molecule’s Optical Absorbance Using Surface Plasmonics
摘要： Understanding the interaction of light with molecules physisorbed on substrates is a fundamental problem in photonics, with applications in biosensing, photovoltaics, photocatalysis, plasmonics, and nanotechnology. However, the design of novel functional materials in silico is severely hampered by the lack of robust and computationally efficient methods for describing both molecular absorbance and screening on substrates. Here we employ our hybrid G0[W0 + ?W]-BSE implementation, which incorporates the substrate via its screening ?W at both the quasiparticle G0W0 level and when solving the Bethe-Salpeter equation (BSE). We show this method can be used to both efficiently and accurately describe the absorption spectra of physisorbed molecules on metal substrates and thereby tailor the molecule’s absorbance by altering the surface plasmon’s energy. Specifically, we investigate how the optical absorption spectra of three prototypical π-conjugated molecules: benzene (C6H6), terrylene (C30H16) and fullerene (C60), depends on the Wigner-Seitz radius rs of the metallic substrate. To gain further understanding of the light–molecule/substrate interaction, we also study the bright exciton’s electron and hole densities and their interactions with infrared active vibrational modes. Our results show that (1) benzene’s bright E1 2u exciton at 7.0 eV, whose energy is insensitive to changes in rs, could be relevant for photocatalytic dehydrogenation and polymerization reactions, (2) terrylene’s bright B3u exciton at 2.3 eV hybridizes with the surface plasmon, allowing the tailoring of the excitonic energy and optical activation of a surface plasmon-like exciton, and (3) fullerene’s π ? π? bright and dark excitons at 6.4 and 6.8 eV hybridize with the surface plasmon, resulting in the tailoring of their excitonic energy and the activation of both a surface plasmon-like exciton and a dark quadrupolar mode via symmetry breaking by the substrate. This work demonstrates how a proper description of interfacial light–molecular/substrate interactions enables the prediction, design, and optimization of technologically relevant phenomena in silico.
关键词： Plasmonics,Optical Absorbance,π-conjugated molecules,Fullerene,Excitons,Hybrid Materials,Benzene,Surface Plasmonics,Magnetic,Infrared active vibrational modes,Wigner-Seitz radius,Optical,Terrylene
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - Athens, Greece (4–6 September 2019)] TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - I-V characteristics of n-Si /ZnO/Se/MWCNTs nanocomposite solar cell fabricated by solvothermal technique
摘要： I-V Characteristics of n-Si/ZnO/Se/MWCNTs nanocomposite solar cell fabricated by solvothermal technique were investigated, deals with the fabrication of heterojunction solar cell was by deposited ZnO-Se-MWCNTs nanocomposite on the n-Si substrate using Pulsed Laser Deposition technique. FE-SEM images show that the diameters of the prepared MWCNTs is up to several micrometers in length and also some of ZnO and Se NPs were closely linked to the surface of MWCNTs. So, the diameter of the coated MWCNTs was increased as a result. XRD shows that the prepared ZnO-Se-MWCNTs nanocomposite has a homogeneous structure with average crystallite sizes (30.86-56) nm. UV-Vis. Spectra show enhancement of absorption for ZnO-Se-MWCNTs nanocomposite material in comparison with MWCNTs. The characteristics of current-voltage heterojunction showed that the forward bias current change nearly exponentially with the applied voltage in dark and this is consistent with tunneling –recombination model. The fill factor of the fabricated n-Si/ZnO/Se/MWCNTs nanocomposite solar cell was 50 %, while the efficiency η was 7 under illumination.
关键词： solar cell,hybrid materials,MWCNTs
更新于2025-09-16 10:30:52
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Bimetallic PtSe nanoparticles incorporating with reduced graphene oxide as efficient and durable electrode materials for liquid-junction photovoltaic devices
摘要： In this work, we introduce the synthesis of PtSe alloys with the different stoichiometric ratio of Pt and Se in PtSe alloy on reduced graphene oxide (RGO). And, then the developed nanohybrid materials are employed for the first time as counter electrodes (CEs) for efficient third-generation solar cells. As a result, PtSe nanoalloys is located on the surface of RGO without any agglomerations. Furthermore, the developed materials also provide a porous three-dimensional network structure, suggesting rapid electron transfer paths. Therefore, the highest efficiency of 6.26% was obtained for a cell fabricated with Pt0$74Se0.26/RGO electrode that is due to the lowest charge-transfer resistance of 0.89 U and diffusion impedance of 0.88 U. The optimized efficiency is also higher than those of 4.98% and 4.34% for devices assembled with Pt/RGO and Se/RGO CEs, respectively. This work presents a general strategy for designing and fabricating porous PtSe alloy/RGO CEs for energy conversion devices.
关键词： PtSe/graphene,Hybrid materials,Counter electrode,Dye-sensitized solar cells
更新于2025-09-16 10:30:52
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Enhanced Resonant Faraday Rotation in Multilayer Magnetoplasmonic Nanohole Arrays and Their Sensing Application
摘要： The optical and magneto-plasmonic properties of Ag/Co and Ag/Co/Ag multilayer nano-hole arrays have been investigated. By including a top- and bottom-Ag plasmonic layer onto a Co ferromagnetic perforated film, strong extraordinary optical transmission peaks and Wood’s anomalies (transmission minima) at both film-air and film-glass interfaces of the film are observed. The coupling between plasmonics and magneto-optics in the arrays gives rise to several resonantly enhanced Faraday rotation peaks that are much sharper than the plasmonic peaks/dips. The rotation peaks appeared exactly at the transmission minima have widths as narrow as 13 nm, which are much narrower than the transmission peaks (> 100 nm) and the accompanying transmission dips (~ 52 nm). The narrow line width of this enhanced Faraday rotation peak allows at least 2 times enhancement of the sensing performance, which is characterized by figure of merit, in compare to any other features of the optical transmission spectra.
关键词： Magnetic,Nano-Hole Arrays,Sensing Application,Hybrid Materials,Plasmonics,Magneto-Plasmonic,Faraday Rotation,Optical
更新于2025-09-12 10:27:22
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Nanostructured Au(111)/Oxide Epitaxial Heterostructures with Tailoring Plasmonic Response by a One-Step Strategy
摘要： In this work we present a strategy for developing epitaxial incommensurate nanostructured-Au/oxide heterostructures with tuneable plasmonic response. Previously high quality single phase and oriented α-Fe2O3(0001) thin films were achieved, which have been used as a template for the noble metal epitaxial deposition. The complex systems have been grown by pulsed laser deposition on two different type of oxide substrates: α-Al2O3(0001) and SrTiO3(111). A one-step procedure has been achieved tailoring the isolated character and the morphological features of Au nanostructures through the substrate temperature during the Au growth, without altering the structural characteristics of the hematite layer that is identified as single iron oxide phase. The epitaxial character and the lattice coupling of Au/oxide bilayers are mediated through the sort of oxide substrate. Single oriented Au(111) islands are disposed with a rotation of 30o between their crystallographic axes and those of α-Fe2O3(0001). The Au(111) and SrTiO3(111) lattices are collinear while a rotation of 30o happens respect to the α-Al2O3(0001) lattice. The crystallographic domain size and crystalline order of hematite structure and Au nanostructured-layer are dependent on the substrate type and the Au growth temperature respectively. Besides, the functional character of the complex systems has been tested. The localized surface plasmons related to Au nanostructures are excited and controlled through the fabrication parameters, tuning the optical resonance with the degree of Au nanostructuring.
关键词： Tailoring Plasmonic Response,Oxide Epitaxial Heterostructures,Nanostructured Au,One-Step Strategy,Plasmonics,Hybrid Materials,Optical,Magnetic
更新于2025-09-12 10:27:22
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Development of Plasmonic Chitosan-Squarate Hydrogels via Bio-Inspired Nanoparticle Growth
摘要： We report on the bio-inspired growth of gold nanoparticles (GNPs) in biocompatible hydrogels to develop plasmonic hybrid materials. The new hydrogel (CS-Sq) is prepared from chitosan and diethylsquarate and is formed via non-covalent interactions rising between the in-situ formed ionic squaric acid derivatives and chitosan. Interestingly, when the hydrogel is prepared in the presence of HAuCl4, GNPs with controlled sizes between 15 and 50 nm are obtained which are homogeneously distributed within the plasmonic hydrogels (GNPs-CS-Sq). We found that the supramolecular nature and the composition of the CS-Sq hydrogels are key for the GNPs growth process where the squaric derivatives act as reducing agents and the chitosan hydrogel network provides nucleation points and supports the GNPs. Accordingly, the hydrogel acts as a bio-inspired reactor and permits to gain certain control on the GNPs size by adjusting the concentration of chitosan and HAuCl4. Besides the intrinsic and tunable plasmonic properties of the GNPs-CS-Sq hydrogels, it was found that the gels could be useful as heterogeneous catalysts for organic reactions. Furthermore, cell viability studies indicate that the new hydrogels exhibit suitable biocompatibility. Thus, the proposed method for obtaining GNPs-CS-Sq hydrogels has the potential to be applied for the development of a wide variety of other hybrid chitosan materials useful for catalysis, biosensing, cell culture, tissue engineering, and drug delivery applications.
关键词： Chitosan,Hybrid Materials,Hydrogels,Squaric Acid,Gold Nanoparticles
更新于2025-09-12 10:27:22
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Precursor-Mediated Synthesis of Shape-controlled Colloidal CsPbBr <sub/>3</sub> Perovskite Nanocrystals and their Nanofiber-Directed Self-assembly
摘要： Shape control is often necessary to tune the optical and electronic properties of nanocrystals (NCs) and is mostly achieved through manipulation of surface ligands and processing conditions. Here we present a versatile synthesis of colloidal CsPbBr3 perovskite NCs of various shapes (nanorods, nanocubes and nanoplatelets) from an inexpensive steroidal Cs precursor: cesium cholate (CsCh). Cesium cholate has several advantages over the most commonly used Cs-precursor (cesium oleate or Cs2CO3 or CsOAc) such as low-cost, non-hygroscopicity and better reproducibility in the perovskite synthesis. Due to the solubility of this Cs-precursor in polar solvents such as methanol, a miniscule polar environment is created during the nucleation and growth of the nanocrystals leading to the serendipitous formation of nanorods at 180 ℃, whereas using a biphasic mixture of 1-octadecene and methanol, the morphology changes to nanocubes. By lowering the reaction temperature (90 ℃), nanoplatelets with 8-9 monolayers thicknesses are formed. These colloidal NCs of variety of shapes are strongly luminescent with a green emission having narrow emission linewidths (16-17 nm) and high quantum yields (96% for nanocubes, 94% for nanoplatelets). Furthermore, hybrid materials of nanocubes and organogel of a dimeric bile acid-derived ester gelator are obtained through co-assembly in which nanocubes arrange along nanofibers with stable, sharp and bright green emission. This enables spatial ordering of nanocubes ranging from micron to centimeter scale in thin films, which is crucial for advanced optoelectronic applications. To date, there is no report in literature on the anisotropic organization of perovskite CsPbBr3 nanocubes triggered by supramolecular co-assembly involving organogel nanofibers.
关键词： nanocubes,organogel,Shape control,hybrid materials,nanorods,cesium cholate,nanoplatelets,supramolecular co-assembly,colloidal CsPbBr3 perovskite NCs
更新于2025-09-12 10:27:22
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The Role of Particle Size in the Dispersion Engineering of Plasmonic Arrays
摘要： Grazing diffraction orders on metal gratings give rise to peculiar optical effects that were contemplated by Wood, Rayleigh and Fano. With plasmonic nanoparticles as resonant grating elements, the phenomenology of such surface lattice resonances becomes quite rich, including spectrally narrow extinction peaks and optical band gap formation. It has been observed that at perpendicular incidence either the higher or lower energy branch corresponding to the first grazing diffraction orders is bright, i.e., couples strongly to light. Reviewing the literature, it appears that particle size is the factor determining which dispersion branch lights up. However, a consistent explanation for this effect is lacking. After revisiting the effect experimentally and by numerical simulation, we clarify the underlying physics by analyzing nanoparticle gratings in terms of, first, an oscillator model and, second, a photonic crystal description. Both approaches reveal the central role of a particle-size-dependent phase shift in the back-scattering of grazing light fields by the particle grating. This phase shift determines the symmetry of the resulting field profiles corresponding to the dispersion branches and thus their ability to couple to the exciting light. This physical understanding could considerably simplify the dispersion engineering of plasmonic nanoparticle gratings for specific applications as sensing or lasing.
关键词： Surface lattice resonances,Hybrid Materials,Magnetic,Optical,Dispersion engineering,Plasmonics,Plasmonic nanoparticles
更新于2025-09-12 10:27:22
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Plasmonic Trimers for Dual-Frequency Surface-Enhanced Two-dimensional Infrared Spectroscopy
摘要： Extension of surface-enhanced two-dimensional infrared spectroscopy (SE-2DIR) to dual-frequency experiments allows to study dynamics and energy transport in thin molecular films by tagging and probing vibrational modes on different sites of the molecule. Measurements of cross-peaks involving transitions largely separated in frequency by SE-2DIR require plasmonic nanostructures with resonant excitations at the corresponding frequencies, where the associated enhanced near-fields spatially overlap and different molecular transitions are simultaneously enhanced in the same molecule. Gold trimer infrared antennas localize enhanced fields within the gap formed by their arms. We exploit the symmetry of trimer antennas to individually tune frequencies of the in-plane plasmonic excitations to match molecular transitions of interest. Dual-frequency SE-2DIR measurements are demonstrated on 4-azidobutyrate-N-hydroxysuccinimide ester with the cross-peaks between the carbonyl and azido stretching vibrational modes, separated by 370 cm-1, and the carbonyl and C-N-C stretching modes, separated by 550 cm-1. Excitation with cross-polarized laser pulses allows to selectively access appropriate plasmon excitations in resonance with the relevant molecular transitions. Our approach, based on the rational plasmon mode engineering, achieves significant enhancement of the cross-peak signals involving largely-separated transition frequencies, which is not possible with single broadband plasmon modes.
关键词： Surface-Enhanced Two-dimensional Infrared Spectroscopy,Dual-frequency,Molecular transitions,Cross-peaks,Gold trimer infrared antennas,Plasmonics,Hybrid Materials,Optical,Magnetic
更新于2025-09-11 14:15:04
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Direct Detection of Bacteria Using Positively-charged Ag/Au Bimetallic Nanoparticles: A Label-Free SERS Study Coupled with Multivariate Analysis
摘要： Rapid detection and discrimination of pathogenic bacteria for food safety, environmental pollution, medical diagnoses, and chemical and biological threats remains a considerable challenge. In the present work, we demonstrate positively charged Ag/Au bimetallic nanoparticles (Ag/Au bmNPs) as a potential surface-enhanced Raman scattering (SERS) substrate for label-free detection and discrimination of three bacteria, viz., Escherichia coli, Salmonella typhimurium and Bacillus subtilis with excellent reproducibility. The approach relies on a priori synthesis of Ag/Au bmNPs and subsequent SERS studies on bacteria. The positive surface charge on Ag/Au bmNPs offers significant advantages of short acquisition time at very low power, high sensitivity, and simple operating procedure without the need of very specific procedures/protocols used to capture the bacteria. The reproducible and specific intrinsic fingerprint of the cell wall and intracellular components of three bacteria obtained by label-free SERS enables precise discrimination and classification of three bacteria using multivariate analysis such as principal component analysis and canonical discriminant analysis.
关键词： SERS,multivariate analysis,Optical,Magnetic,label-free study,and Hybrid Materials,bacteria detection,Ag/Au bimetallic nanoparticles,Plasmonics
更新于2025-09-11 14:15:04