Enhanced Surface Plasmon Resonance Research Articles

Design of an efficient ultra-thin film Cu(In,Ga)Se2 solar cell, using plasmonic cluster back reflectors

In this paper, an ultra-thin film CIGS solar cell using a cluster back reflector is discussed to improve optical parameters. This cluster nanostructure includes four silver nanoparticles embedded in the back surface of the active layer. By optimizing the effective parameters of the plasmonic phenomenon, such as length, width, height, and distances between the nanoparticles, among the studied cases, the cylindrical nanostructure, is selected as the most efficient back reflector. To achieve these results, it is mainly focused on short-circuit current density analysis. Besides, power conversion efficiency, absorption spectrum and transmission of light are also studied. As a result, due to the localized surface plasmon resonance enhancement, short-circuit current density and power conversion efficiency reach 27.2 mA/cm2 and 15.7 %, respectively. These values for the bare state were 19 mA/cm2 and 10.7 %.

Plasmon Tunability and Field Enhancement of Gold Nanostar

Objective: The localized surface plasmon resonance (LSPR) and field enhancement of Gold nanosphere and nanostar were evaluated. Method: FDTD solutions, a product of Lumerical solutions Inc., Vancouver, Canada [17], was used to perform the electromagnetic simulations in this work. The impact of particle size and spike number on peak wavelength was studied quantitatively. Result: By altering the particle size and amount of spikes, we were able to detect a hot zone around nanostar. For Au nanostar, the peak wavelength for nanostar varies from visible to near-infrared. When compared to a nanosphere of the same dimension, the shift seen in nanostar is substantially higher, making it more suitable for biosensing applications. When the refractive index of the surrounding medium is increased, a red shift in peak wavelength is noticed, forming the basis for a plasmonic refractive index sensor. Aside from having a higher sensitivity, nanostar has a twofold hot spot system due to their unique surfaces. There is no evidence of spike aggregation in the near field pattern. As a result, it is thought to be a better nanostructure for biosensing applications. Conclusion: The LSPR and field enhancement for Au nanosphere and Nanostar were investigated using the FDTD method. The nanosphere's peak wavelength is in visible region, whereas the nanostar's range extends from visible to near-infrared, depending on the size and number of spikes. At 517 nm, the enhancement factor for a nanosphere was 102, but at 1282 nm, the enhancement factor for a nanostar with six spikes was 108.

Highly sensitive plasmonic biosensor enhanced by perovskite-graphene hybrid configuration

This study theoretically proposes a highly sensitive plasmonic biosensor comprising a silver film, perovskite nanosheets, bi-layer silicon nanosheets, and a graphene overlayer. The introduction of perovskite-graphene hybrid structure can reduce the optical reflectivity of the proposed biosensor configuration so that photons are converted into energy to support surface plasmon resonance (SPR) enhancement. Unlike conventional angular modulation, our proposed biosensor configuration is designed using phase modulation, offering sensitivity enhancements as high as 3 orders of magnitude. Excellent biosensing performances have been examined by optimizing the silver film thickness and the number of perovskite nanosheets. Considering a tiny refractive index change of 0.0012 refractive index unit (RIU) caused by biomolecules adsorption behavior, the optimal plasmonic biosensor configuration of 46-nm silver film–5.7-nm silicon interlayer-1-layer CH3NH3PbI3 perovskite film–0.7-nm silicon interlayer-1-layer graphene can produce the highest detection sensitivity of 1.2314 × 105 degree/RIU. In addition, an excellent linear response in the differential phase can be obtained, as the refractive index variation of the sensing interface can be as low as 10−6 RIU, showing great potential in performing ultrasensitive biosensing.

In Operando Photoswitching of Cu Oxidation States in Cu-Based Plasmonic Heterogeneous Photocatalysis for Efficient H2 Evolution.

Metal nanoparticles (NP) supported on TiO2 are known to be efficient photocatalysts for solar-to-chemical energy conversion. While TiO2 decorated with copper NPs has the potential to become an attractive system, the poor oxidative stability of Cu severely limits its applicability. In this work, we demonstrate that, when Cu NPs supported on TiO2 nanobelts (NBs) are engaged in the photocatalytic generation of H2 from water under light illumination, Cu is not only oxidized in CuO but also dissolved under the form of Cu+/Cu2+ ions, leading to a continuous reconstruction of nanoparticles via Ostwald ripening. By nanoencapsulating the CuOx (Cu/CuO/Cu2O) NPs by a few layers of carbon supported on TiO2 (TC@C), Ostwald ripening can be suppressed. Simultaneously, the resulting CuOx@C NPs are photoreduced under light illumination to generate Cu@C NPs. This photoswitching strategy allows the preparation of a Cu plasmonic photocatalyst with enhanced activity for H2 production. Remarkably, the photocatalyst is even active when illuminated with visible light, indicating a clear plasmonic enhancement of photocatalytic activity from the surface plasmonic resonance (SPR) effect of Cu NPs. Three-dimensional electromagnetic wave-frequency domain (3D-EWFD) simulations were conducted to confirm the SPR enhancement. This advance bodes for the development of scalable multifunctional Cu-based plasmonic photocatalysts for solar energy transfer.

Surface plasmon resonance based on graphene-metal-graphene structure: recurrence relation theory

The last years, graphene has opened exciting new fields in graphene plasmonics, due to the graphene’s unique optoelectronic properties such as long-lived collective excitation, extreme optical confinement in graphene plasmonics and extraordinary light-matter interactions in metamaterials. Therefore, these excellent properties make graphene a favorable candidate for novel plasmonic devices and potential applications in photonics, optoelectronics and sensor technologies. In this work, theoretical investigations are carried out to in Graphene-Metal-Graphene structure for enhanced surface plasmon resonance based on the recurrence relations’ method. We find that the graphene-metal-graphene structure supports both high-energy optical plasmon oscillations and out-of-phase low energy acoustic charge density excitations. Since a high performance of surface plasmon resonance excitations should exhibit a large depth of dip (small reflectivity), the minimum of reflectivity in the hybrid structure can be manipulated dynamically by changing the thickness of the metallic film, the number of the graphene layers and the dielectric proprieties of the surrounding dielectric materials. Based on this principle, different kinds of plasmonic sensors have been designed in previous years.

Advanced electrochromic properties of Nb-doped WO3 inverse opal films in NIR region by slow photon effect-assisted enhancement of localized surface plasmon resonance

Among various methods to enhance light harvest, opal and inverse opal with periodicity in structure are indisputable one of the best solutions. In this view, inverse opal (IO) was introduced in Nb-doped WO3 film to assist localized surface plasmon resonance (LSPR), aiming to enhance electrochromic optical contrast in near infrared (NIR) region. The obtained Nb-doped WO3 inverse opal (IO) film demonstrates its advantage with an optical contrast of 60.4% at 1100 nm wavelength, nearly twice higher than its plain film counterpart (29.1%) and 5 times higher than undoped WO3 IO film (11%). Such extraordinary property is attributed to slow photon effect assisted enhancement of LSPR: in addition to oxygen vacancies due to Nb dopant, a much longer lifetime of free carriers (11.84 ns) arising from slow photon effect of inverse opal, which is double to that of its plain film counterpart (6.72 ns), renders a great increase in photonic absorption and further an enhancement of LSPR under light incident condition. The success of present strategy can be extended to rationally design other related devices.

Low-Temperature Direct Growth of Nanocrystalline Multilayer Graphene on Silver with Long-Term Surface Passivation.

A wide variety of transition metals, including copper and gold, have been successfully used as substrates for graphene growth. On the other hand, it has been challenging to grow graphene on silver, so realistic applications by combining graphene and silver for improved electrode stability and enhanced surface plasmon resonance in organic light-emitting diodes and biosensing have not been realized to date. Here, we demonstrate the surface passivation of silver through the single-step rapid growth of nanocrystalline multilayer graphene on silver via low-temperature plasma-enhanced chemical vapor deposition (PECVD). The effect of the growth time on the graphene quality and the underlying silver characteristics is investigated by Raman spectroscopy, X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and cross-sectional annular dark-field scanning transmission electron microscopy (ADF-STEM). These results reveal nanocrystalline graphene structures with turbostratic layer stacking. Based on the XPS and ADF-STEM results, a PECVD growth mechanism of graphene on silver is proposed. The multilayer graphene also provides excellent long-term protection of the underlying silver surface from oxidation after 5 months of air exposure. This development thus paves the way toward realizing technological applications based on graphene-protected silver surfaces and electrodes as well as hybrid graphene-silver plasmonics.

Enhancement of elastic properties and surface plasmon resonance with the addition of boron oxide to the ZnO−SiO2 glass system

Glass substrates, with their ultrasonic and enhanced Raman signals, are ever-demanding for medical applications. This paper reports the effect of boron addition to the enhancement of the elastic properties and Raman shifting in the Surface Plasmon Resonance results for the zinc borosilicate glass substrate that can be used for optical biosensor applications. Such glasses were prepared by melt–the quenching method and characterized using a densimeter, X-ray diffraction measurement, Fourier transforms infrared spectroscopy, ultrasonic, and surface plasmon resonance spectroscopy. Results from the current study demonstrated how the composition of the glass influences the physical and elastic moduli of the boron-doped zinc silicate series. The physical characteristics of the zinc silicate glasses were predicted to alter significantly after adding boron as a modifier. The glass density decreased from 3392 to 2983 kg/m3 as the percentage of boron increased from 0.10 to 0.20 wt.%, then increased to 3191 kg/m3 at 0.30 wt.%. The X-ray diffraction and Fourier transforms infrared spectroscopy techniques verified the amorphous glass phase. The ultrasonic method determined the glass's ultrasonic longitudinal and shear velocity at a 5 MHz resounding recurrence at room temperature to study elastic moduli. When boron content is added, the longitudinal, Young, shear, and bulk moduli exhibit a decreasing and increasing trend. As the boron content increases and behaves as a modifier, the number of non-bridging oxygen will increase, which will cause the glass network to expand. In addition, the increase in Eopt occurs from 3.4883 to 3.4331 because the sample has a higher number of non-bridging oxygen. The shift for Otto configuration of the SPR results occurs with the increase of boron concentration. The fabricated glass can potentially be used to construct an integrated silicon-based glass substrate for an optical sensor.

Recent Progress in Plasmonic based Electrochemiluminescence Biosensors: A Review

Electrochemiluminescence (ECL) analysis has become a powerful tool in recent biomarker detection and clinic diagnosis due to its high sensitivity and broad linear range. To improve the analytical performance of ECL biosensors, various advanced nanomaterials have been introduced to regulate the ECL signal such as graphene, gold nanomaterials, and quantum dots. Among these nanomaterials, some plasmonic nanostructures play important roles in the fabrication of ECL biosensors. The plasmon effect for the ECL signal includes ECL quenching by resonant energy transfer, ECL enhancement by surface plasmon resonance enhancement, and a change in the polarized angle of ECL emission. The influence can be regulated by the distance between ECL emitters and plasmonic materials, and the characteristics of polarization angle-dependent surface plasmon coupling. This paper outlines the recent advances of plasmonic based ECL biosensors involving various plasmonic materials including noble metals and semiconductor nanomaterials. The detection targets in these biosensors range from small molecules, proteins, nucleic acids, and cells thanks to the plasmonic effect. In addition to ECL biosensors, ECL microscopy analysis with plasmonic materials is also highlighted because of the enhanced ECL image quality by the plasmonic effect. Finally, the future opportunities and challenges are discussed if more plasmonic effects are introduced into the ECL realm.

Rapid fabrication of interdigitated electrodes by laser ablation with application to electrokinetically enhanced surface plasmon resonance imaging

SignificanceDielectrophoresis, electro-osmosis, and other electrokinetic effects are frequently used in a variety of applications but necessitate patterning of electrodes on sensor surfaces. This typically requires a cleanroom and time-consuming, expensive, and arcane lithography and etching procedures. AimTo demonstrate the applicability of commercial laser direct writing equipment for rapid patterning of electrodes into gold layers on glass substrates, particularly with application to producing electrokinetically active plasmonic sensors. ApproachA commercial printed circuit board prototyper was used to pattern interdigitated electrode (IDE) arrays into the surface of gold-coated slides and off-the-shelf surface plasmon resonance (SPR) prisms. The electrode geometries resulting from different patterning parameters were characterized by profilometry and electron microscopy. The patterned surfaces were then employed for trapping and electro-kinetic manipulation of bacteria, and finally for sensing of bacteria by SPR imaging. ResultsFabrication of an IDE array can be completed in as little as 12 s, with longer fabrication times permitting superior geometry and minimum feature size of 15 µm. The patterned IDEs were capable of concentrating bacteria and controlling their position on the sensor surface as a function of applied frequencies. SPR was demonstrated to detect specific interactions between bacteria and immobilized antimicrobial peptides. ConclusionsLaser direct writing is demonstrated as a feasible, cleanroom-free alternative to more lengthy lithography methods, permitting very rapid fabrication and prototyping of IDEs, which are compatible with active plasmonic sensing and bacterial detection.

Characterisation of a micrometer-scale active plasmonic element by means of complementary computational and experimental methods.

In this article, we investigate an active plasmonic element which will act as the key building block for future photonic devices. This element operates by modulating optical constants in a localised fashion, thereby providing an external control over the strength of the electromagnetic near field above the element as well as its far-field response. A dual experimental approach is employed in tandem with computational methods to characterise the response of this system. First, an enhanced surface plasmon resonance experiment in a classical Kretschmann configuration is used to measure the changes in the reflectivity induced by an alternating electric current. A lock-in amplifier is used to extract the dynamic changes in the far-field reflectivity resulting from Joule heating. A clear modulation of the materials' optical constants can be inferred from the changed reflectivity, which is highly sensitive and dependent on the input current. The changed electrical permittivity of the active element is due to Joule heating. Second, the resulting expansion of the metallic element is measured using scanning Joule expansion microscopy. The localised temperature distribution, and hence information about the localisation of the modulation of the optical constants of the system, can be extracted using this technique. Both optical and thermal data are used to inform detailed finite element method simulations for verification and to predict system responses allowing for enhanced design choices to maximise modulation depth and localisation.

3D substoichiometric MoO3−x/EGaln framework for room temperature NH3 gas sensing

Though conventional metal oxide-based NH3 gas sensors possess the advantage of simplicity and high sensitivity, their relatively high operating temperature still limits their widespread applications. Therefore, it is essential to develop a reliable NH3 sensor that operated at room temperature. In this context, we employ the ultrasonic method to coat the sonication-prepared substoichiometric molybdenum trioxide (MoO3−x) nanosheets upon the eutectic gallium indium (EGaIn) microdroplets, thus forming a three-dimensional (3D) MoO3−x/EGaIn semiconducting liquid metal framework. Due to the high surface-reducing properties of EGaIn, the concentration of oxygen vacancies in MoO3−x is further increased, presenting enhanced surface plasmon resonance in the visible light range. Such a plasmonic oxide framework (POF) exhibits a response magnitude of 1.22 for 50 ppm NH3 at room temperature with almost complete recovery, high selectivity, and excellent repeatability under the blue light excitation. It is remarkable that room temperature optoelectronic gas sensing performance is rarely seen in pure metal oxides. This work not only provides a promising NH3 gas sensing material but also demonstrates the great potential of liquid metal/semiconductor contacts for room temperature reversible gas sensing.

A high-performance UV photodetector with superior responsivity enabled by a synergistic photo/thermal enhancement of localized surface plasmon resonance

We report the development of a high-performance UV photodetector based on W18O49/TiO2 nanofibers enabled by plasmon-induced synergistic photo/thermal enhancement; the responsivity of this device significantly exceeds those of TiO2-based photodetectors reported to date.

Design of broadband high efficiency absorption antenna based on metamaterial nano-ring array

Compared with the traditional solar cells, the nano-optical antenna breaks through the band-gap limitation of semiconductor materials, and provides a new scheme for solar energy collection. In order to solve the problems of complex structure, low efficiency and narrow bandwidth of nano-optical antenna, a novel nano-ring-cylinder based on metamaterials is proposed in this paper. The antenna has an average absorption efficiency of 96.93% in the wide-band absorption range of visible and near-infrared light. First of all, the basic design theory of the antenna was given based on the surface plasma theory. Then, the antenna structure design scheme was determined, the overall structure consists of two layers of metal and an insulating layer formed by Al2O3. Finally, on the basis of the established antenna model, the absorption characteristics were analyzed by simulation. The analysis result shows that the super-absorption ability of the antenna is independent of the polarization of the incident light, and the average absorption ability can be maintained at about 91% when the incident angle is ±60°. The absorption capability of the antenna is mainly due to the synergistic effect of Fabry-Perot resonance and localized surface plasmon resonance enhancement. The conclusion can provide a theoretical guidance for the structural design of nano-optical antenna.

Plasmon-Induced Semiconductor-Based Photo-Thermal Catalysis: Fundamentals, Critical Aspects, Design, and Applications

Photo-thermal catalysis is among the most effective alternative pathways used to perform chemical reactions under solar irradiation. The synergistic contributions of heat and light during photo-thermal catalytic processes can effectively improve reaction efficiency and alter design selectivity, even under operational instability. The present review focuses on the recent advances in photo-thermal-driven chemical reactions, basic physics behind the localized surface plasmon resonance (LSPR) formation and enhancement, pathways of charge carrier generation and transfer between plasmonic nanostructures and photo-thermal conversion, critical aspects influencing photo-thermal catalytic performance, tailored symmetry, and morphology engineering used to design efficient photo-thermal catalytic systems. By highlighting the multifield coupling benefits of plasmonic nanomaterials and semiconductor oxides, we summarized and discussed several recently developed photo-thermal catalysts and their catalytic performance in energy production (CO2 conversion and H2 dissociation), environmental protection (VOCs and dyes degradation), and organic compound synthesis (Olefins). Finally, the difficulties and future endeavors related to the design and engineering of photo-thermal catalysts were pointed out to draw the attention of researchers to this sustainable technology used for maximum solar energy utilization.

Nanoformulation of Tetrapyrroles Derivatives in Photodynamic Therapy: A Focus on Bacteriochlorin.

Photodynamic therapy (PDT) is a well-known remedial treatment for cancer, infections, and various other diseases. PDT uses nontoxic dyes called photosensitizers (PS) that are activated in visible light at the proper wavelength to generate ROS (reactive oxygen species) that aid in killing tumor cells and destroying pathogenic microbes. Deciding a suitable photosensitizer is essential for enhancing the effectiveness of photodynamic therapy. It is challenging to choose the photosensitizer that is appropriate for specific pathological circumstances, such as different cancer species. Porphyrin, chlorin, and bacteriochlorin are tetrapyrroles used with proper functionalization in PDT, among which some compound has been clinically approved. Most photosensitizers are hydrophobic, have minimum solubility, and exhibit cytotoxicity due to the dispersion in biological fluid. This paper reviewed some nanotechnology-based strategies to overcome these drawbacks. In PDT, metal nanoparticles are widely used due to their enhanced surface plasmon resonance. The self-assembled nano-drug carriers like polymeric micelles, liposomes, and metal-based nanoparticles play a significant role in solubilizing the photosensitizer to make them biocompatible.

Magnetic Alignment for Plasmonic Control of Gold Nanorods Coated with Iron Oxide Nanoparticles.

Plasmonic nanoparticles that can be manipulated with magnetic fields are of interest for advanced optical applications, diagnostics, imaging, and therapy. Alignment of gold nanorods yields strong polarization-dependent extinction, and use of magnetic fields is appealing because they act through space and can be quickly switched. In this work, cationic polyethyleneimine-functionalized superparamagnetic Fe3 O4 nanoparticles (NPs) are deposited on the surface of anionic gold nanorods coated with bovine serum albumin. The magnetic gold nanorods (MagGNRs) obtained through mixing maintain the distinct optical properties of plasmonic gold nanorods that are minimally perturbed by the magnetic overcoating. Magnetic alignment of the MagGNRs arising from magnetic dipolar interactions on the anisotropic gold nanorod core is comprehensively characterized, including structural characterization and enhancement (suppression) of the longitudinal surface plasmon resonance and suppression (enhancement) of the transverse surface plasmon resonance for light polarized parallel (orthogonal) to the magnetic field. The MagGNRs can also be driven in rotating magnetic fields to rotate at frequencies of at least 17Hz. For suitably large gold nanorods (148nm long) and Fe3 O4 NPs (13.4nm diameter), significant alignment is possible even in modest (<500Oe) magnetic fields. An analytical model provides a unified understanding of the magnetic alignment of MagGNRs.

Checkerboard-like nickel nanoislands/defect graphene aerogel with enhanced surface plasmon resonance for superior microwave absorption

To solve the problem of dispersion of magnetic nanoparticles in ultralight electromagnetic absorption field, checkerboard-like nickel nanoislands/defect graphene aerogel (NIDG) with enhanced surface plasmon resonance was designed and prepared through electrostatic self-assembly method. This special structure successfully overcame the aggregation phenomenon of magnetic metals and built high-density gap regions to enhance surface plasmon resonance. And the NIDG has achieved excellent electromagnetic wave absorption performance in C band. Specially, NIDG is superior in ultra-lightness with only 6.2 wt%, compared to some recently reported magnetic electromagnetic wave absorbers. Such great performance can be attributed to the enhanced surface plasmon resonance and improved impedance matching. This work is significant for achieving effective dielectric loss and designing lightweight low-frequency EMW absorbing materials.

Shell-Isolated Nanoparticle-Enhanced Electrochemiluminescence.

Enhanced electrochemiluminescence (ECL) aims to promote higher sensitivity and obtain better detection limit. The core-shell nanostructures, owing to unique surface plasmon resonance (SPR) enabling distance-dependent strong localized electromagnetic field, have attracted rising attention in enhanced ECL research and application. However, the present structures usually with porous shell involve electrocatalytic activity from the metal core and adsorption effect from the shell, which interfere with practical SPR enhancement contribution to ECL signal. Herein, to exclude the interference and unveil exact SPR-enhanced effect, shell-isolated nanoparticles (SHINs) whose shell gets thicker and becomes pinhole-free are developed by modifying pH value and particles concentration. Furthermore, allowing for the distribution of hotspots and stronger enhancement, excitation intensity and ECL reaction layer thickness are mainly investigated, and several types of SHINs-enhanced ECL platforms are prepared to fabricate distinct hotspot distribution via electrostatic attraction (submonolayer) and a layer-by-layer deposition method (monolayer). Consequently, the strongest enhancement up to ≈250-fold is achieved by monolayer SHINs with 10nm shell, and the platform is applied in a "turn-off" mode sensing for dopamine. The platform provides new guidelines to shell preparation, interface engineering and hotspots fabrication for superior ECL enhancement and analytical application with high performance.

Surface plasmon resonance assisted optical characterization of nickel ion solution and nanocrystalline cellulose-graphene oxide thin film for sensitivity enhancement analysis

In this research, optical characterization of nickel ion solution and nanocrystalline cellulose-graphene oxide (NCC-GO) thin film has been carried out using surface plasmon resonance (SPR). The SPR experiments were carried out using bare gold thin film, in contact with deionized water and nickel ion at different concentrations, followed by the gold/NCC-GO system. Excellent agreement between the theoretical and experimental curves was observed where the real part (n) and the imaginary part (k) of the refractive index (ń) for gold thin film was n˜=0.2165+i3.8122. For nickel ion solution, the n value was similar with deionized water, i.e. 1.3333. Fitting the reflectance curves of gold/NCC-GO system revealed that ń for the NCC-GO thin film was n˜=1.4240+i0.0220. The analysis also showed the NCC-GO contributes to the sensitivity enhancement of SPR towards nickel ion sensing with a sensitivity of 10.8227°/RIU.