Plasmon-enhanced Photoluminescence Research Articles

Plasmon-enhanced photoluminescence spectroscopy of a single molecule in the subnanometer cavity

We investigate the influence of quantum tunneling on the plasmon-enhanced electric field and photoluminescence spectroscopy in the subnanometer nanogap between two adjacent Ag nanoparticles using the quantum-corrected method. We analyze the contribution of nonlocal dielectric response at different separation distances to plasmon-enhanced fluorescence using the D-parameters method. Our results demonstrate the high sensitivity of the quantum-induced effect and nonlocal dielectric response to the separation distance. In cases of shorter separation distances, the localized fields start to decrease due to tunneling current short circuit, resulting in a substantial reduction in Raman enhancement. Additionally, the lower quantum yield caused by loss of electron-hole pairs further quenches the fluorescence intensity in the narrowing gaps. We achieve calculated Raman and fluorescence enhancement factors of 13 and 6 orders of magnitude. Under excitation wavelengths of 660 nm, we achieve spatial resolutions of 1.5 nm and 2.2 nm for Raman and fluorescence spectroscopy.

Plasmon-enhanced photoluminescence and Raman spectroscopy of silver nanoparticles grown by solid state dewetting

The growth of the metallic nanoparticles (NPs) on the solid substrate with the desired shape and size is a critical issue for application of these NPs in solid-state devices. Solid state dewetting (SSD) technique is simple, low cost and can be used to fabricate the metallic NPs with control on the shape and size on different substrates. In this work, silver NPs (Ag NPs) were grown on corning glass substrate by SSD of silver precursor thin film deposited at different substrate temperatures by RF sputtering. The influence of the substrate temperature on the growth of Ag NPs and their several properties like localized surface plasmon resonance (LSPR), photoluminescence (PL), and Raman spectroscopy is studied. The size of the NPs was found to vary from 25 nm to 70 nm with the variation in substrate temperature from room temperature (RT) to . For the RT films, the LSPR peak position of Ag NPs is around 474 nm. A red shift in LSPR peak for films deposited at higher temperature is observed due to change in the particle size and interparticle separation. Photoluminescence spectra suggests the presence of two photoluminescence bands at 436 and 474 nm corresponding to Ag NPs radiative interband transition and LSPR band. An intense Raman peak was observed at 1587 cm−1. Enhancement in PL peak intensity and Raman peak intensity is found to be in accordance with the LSPR of Ag NPs.

Thickness dependence of optical properties of thin multilayer Ag/Bi structures and their surface plasmon-enhanced photoluminescence capability

Preparation technology, optical properties and surface-enhanced photoluminescence features of thin Ag/Bi layers with different ratios of the chemical elements are subject of present work. Coatings with different number of Ag/Bi stacks were tested in order to determine the minimum number of sublayers required to achieve epsilon-near-zero properties (ENZ). The results for the complex permittivity showed that the Ag/Bi films possess epsilon-near-zero properties in a wide spectral range of 1.3-6 eV. It was established that the most promising material for photoluminescence signal amplification is the four stacked Ag50:Bi50 thin layer.

Plasmon-enhanced photoluminescence from MoS2 monolayer with topological insulator nanoparticle

Abstract Topological insulators (TI), as a kind of fantastic nanomaterial with excellent electrical and optical properties, have attracted particular attention due to the promising applications in optoelectronic devices. Herein, we experimentally demonstrated the interaction between light and molybdenum disulfide (MoS2) monolayer with an antimony telluride (Sb2Te3) TI nanoparticle. It was found that photoluminescence (PL) emission and Raman scattering signal can be boosted by 5 and 8 folds in MoS2 monolayer integrated with the TI nanoparticle, respectively. The measured and simulated dark-field scattering spectra illustrated that the enhancement of light–matter interaction could be derived from the generation of localized surface plasmons on the TI nanoparticle with distinctly boosted electric field. We also found that there exists a redshift of 5 nm for the enhanced PL peak, which could be attributed to the formation of trions in MoS2 induced by plasmon doping. This work would provide a new pathway for the applications of TI nanoparticles in the optoelectronics, especially light–matter interaction enhancement.

Combined effects of emitter-emitter and emitter-plasmonic surface separations dictate photoluminescence enhancement in a plasmonic field.

The brightness of an emitter can be enhanced by metal-enhanced fluorescence, wherein the excitonic dipole couples with the electromagnetic field of the surface plasmon. Herein, we experimentally map the landscape of photoluminescence enhancement (EFexp) of emitters in a plasmonic field as a function of the emitter-emitter separation, s, and the emitter-plasmon distance, t. We use Au nanoparticles overcoated with inert spacers as plasmonic systems and CdSe/ZnS quantum dots (QDs) as an emitter bearing opposite surface charges. The t and s are varied by changing the spacer thickness and number density of QDs on the plasmonic surface, respectively. The electrostatic binding of emitters on the plasmonic surface and their number density are established by following the variation of zeta-potential. EFexp is high, when t is short and s is large; nevertheless, it decreases when the emitter-emitter interaction dominates due to plasmon assisted nonradiative processes. In the absence of a plasmonic field, the enhancement observed is attributed to environmental effects and is independent of s, confirming the role of the electric field. Indeed, the distance dependence of EFexp closely follows the decay of the plasmonic field upon dilution of the emitter concentration on nanoparticles' surface (s = 18 nm). The QD-plasmon system is visualized in the framework of the Thomson problem, and classical electrodynamics calculations give the trends in t and s dependence of the photoluminescence. Being the first report on the simultaneous dependence of t and s on plasmon-enhanced photoluminescence, the results presented herein will open newer opportunities in the design of hybrid systems with a high brightness.

Gap surface plasmon-enhanced photoluminescence from upconversion nanoparticle-sensitized perovskite quantum dots in a metal–insulator–metal configuration under NIR excitation

29-Fold luminescence enhancement of upconversion nanoparticle-sensitized perovskite quantum dots was achieved by implementing a metal–insulator–metal configuration and plasmonic coupling.

Plasmon-enhanced photoluminescence from TiO2 and TeO2 thin films doped by Eu3+ for optoelectronic applications.

In this work we study the luminescence properties of europium-doped titanium dioxide and tellurium oxide thin films enhanced by gold plasmonic nanostructures. We propose a new type of plasmon structure with an ultrathin dielectric film between plasmonic platform and luminescent material. Plasmonic platforms were manufactured through thermal annealing of the gold thin film. Thermal dewetting of gold film results in spherical gold nanostructures with average dimensions of 50 nm. Both, luminescent TiO2:Eu and TeO2:Eu films were deposited by RF magnetron sputtering from mosaic targets. The morphology of the gold nanostructures was investigated by SEM and TEM, while the composition of oxides film was analyzed by XPS. Luminescence properties were studied on the basis of excitation and emission spectra. The experiments show that the additional dielectric layer enhances the luminescence intensity. Such structures could be potential candidates as phosphors in white LEDs.

Integration of topological insulator nanogap with atomic single layer for boosting photoluminescence

As a new class of nanomaterials, topological insulators with the Dirac surface conducting state and insulating bulk state offer a promising platform for plasmonics with breaking through the frequency and integration limitation of traditional materials. The combination of topological insulators with atomic-layer materials will be significant for the realization of integrated plasmonic functional devices. Herein, we experimentally report the plasmon-enhanced photoluminescence (PL) emission behavior of molybdenum disulfide (MoS2) single layer integrated with an antimony telluride (Sb2Te3) topological insulator nanogap. It is found that the PL response of MoS2 on the nanogap is dependent on the polarization of incident light. The MoS2 PL intensity can be distinctly improved with plasmonic excitation on Sb2Te3 nanogap. These results will contribute to exploring plasmonic behaviors of topological insulators and their applications in enhanced light-matter interaction for nanoscale light emission and harvesting devices.

Enhanced photoluminescence of DCJTB with ordered Ag-SiO2 core–shell nanostructures via nanosphere lithography

We have fabricated Ag-SiO2 core–shell nanostructure set in the hexagonally ordered Ag nanohole array by nanosphere lithography with reactive ion etching, and followed by Ag deposition. The resulting nanostructure includes the triangular-shaped plates with sharp edges on the top, the Ag-SiO2 core–shell nanospheres, the hexagonally arranged nanohole array, a SiO2 buffer layer and a DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) fluorescent dye layer, respectively. Six patterns of substrates (i.e., Types 1–6) were fabricated and their photoluminescence enhancement performance was compared to substrate layered with pure DCJTB. The experimental results show that photoluminescence enhancement can be 15.69 times, and the lifetime can be shortened from 0.97 ns to 0.41 ns for Type 3 when compared to the pure DCJTB one. The finite element method revealed four structure conditions which are the effects of edge enhancement, gap plasmon resonance, hollow plasmon resonance, and core–shell hybridization plasmon resonance and can contribute to the photoluminescence enhancement factor. The proposed substrates provide a practical detecting platform with plasmon-enhanced photoluminescence, and the fabrication methods used are technically simple and low cost.

Structural properties of Ag-Er3+doped Tungsten Tellurite Glass Ceramics

Tellurite based glasses of composition TeO2-WO3- Li2O-Yb2O3- Er2O3 with different Ag2O (TWLEYA) concentrations has been prepared by melt quenching technique. Heat-treatment process of glass samples was performed to nucleate Ag-NPs and glass-ceramic nature of samples is evidenced by XRD measurement. For glass stability of transition temperature and onset crystallization of this glass, the system has been studied by DSC. Surface plasmon-enhanced photoluminescence in the glasses are measured in the range 535-550 nm green and 640-650nm red under 488nm excitation. Raman spectrum revealed glasses were mainly formed by the [TeO4], {TeO3}, [WO4] and [WO6] units and [TeO4] units convert to [TeO3] units with the addition of WO3 and Li2O into tellurite glasses. The result indicates that enhancement of Raman intensity and a small shift has been grown due to surface plasmon of 12hrs heat-treated Ag nanoparticle doped TWLEYA glass. Thus enhanced optical response of the glass samples with Ag-NPs is attributed to the growth of the local field and vicinity of the nanoparticles on erbium ions. With optimum 0.7 mol%, Ag NPs in TWLEYA glass may be utilized for their potential applications in photonic devices

Plasmonic Nanocavity Metasurface Based on Laser-Structured Silver Surface and Silver Nanoprisms for the Enhancement of Adenosine Nucleotide Photoluminescence

A reliable photoluminescence (PL) spectroscopy and imaging of biomolecules at room temperature is a challenging and important problem of biophysics, biochemistry, and molecular genetics. A unique effect of strong plasmonic enhancement of the PL by metal nanostructures is one of the most effective approaches for this purpose. The highest enhancement is provided by metal nanostructures with densely packed sharp tips, periodically arranged metal nanostructures, and plasmonic cavities. All of these features have been realized in the plasmonic cavity metasurface based on the silver (Ag) laser-induced periodic surface structure and Ag triangular nanoprisms studied in the present work. The strong plasmon-enhanced PL of 5′-deoxyadenosine monophosphate deposited on such metasurfaces has been revealed at room temperature. The observed enhancement of more than 1000-fold has been interpreted as a result of synergetic action of the generation of a high concentration of hot spots near the sharp edges of the laser-induc...

Double plasmon resonance in hybrid structures of silver nanoparticles with amorphous hydrogenated carbon

ABSTRACTIn this work, double plasmon resonances in hybrid structures comprising Ag nanoparticles (NPs) and amorphous hydrogenated carbon films (a-C:H) have been studied. Granulated silver films with a gravimetric thickness of 10 nm were thermally deposited on top or underneath a-C:H films fabricated by plasma-assisted chemical vapour deposition on a quartz substrate. Two plasmon bands with comparable intensities have been observed in the hybrid structures optical density spectrum after annealing at 200°C. On the other hand, in the absence of the amorphous hydrogenated carbon film the short-wavelength peak in the optical density spectrum of the same Ag film is hardly observable. In addition, plasmon-enhanced photoluminescence of the a-C:H film being excited close to the spectral dip at the wavelength of 405 nm was observed. The nature of double plasmon resonance spectra were discussed and explained by the resonance interaction of plasmons excited in Ag NPs with excitons in a-C:H.

Plasmon-enhanced photoluminescence from SnO2 nanostructures decorated with Au nanoparticles

We report significantly enhanced photoluminescence from hybrid nanostructured Au/SnO2 thin films due to surface plasmons excited in Au nanoparticles decorating SnO2 nanostructured thin film. Nanostructured thin films with Au nanoparticles decorated SnO2 nanostructures were prepared by sputter deposition of ultrathin Au films following thermal evaporation of SnO2 film. The effects of deposition of ultrathin film of Au nanoparticles on the morphology, structure and optical response of nanostructured SnO2 film were investigated. Nanocrystalline SnO2, Au, Sn and Au-Sn alloy were revealed by XRD analysis. PL studies revealed that Au nanoparticle decoration of nanostructured SnO2 film led to highly enhanced UV emission. The mechanism of strong enhancement of PL from nanostructured SnO2 film is tentatively proposed. The coupling of excitonic emission from SnO2 nanostructures and excited surface plasmons in Au nanoparticles led to the observed strong PL enhancement. The hybrid nanostructured Au/SnO2 thin films with strong UV emission are promising for designing efficient optical and photoelectrical devices.

Multi-fold plasmon-enhanced photoluminescence of a-C:H thin films

The regularities study of a-C:H film photoluminescence (PL) enhancement by localized surface plasmon resonance (LSPR) in hybrid structures with nanogranulated Ag film was the main aim of this work. We have compared the PL spectra of two thin-film hybrid structures in which the a-C:H optical gap was 2.7 eV and 0.4 eV. The a-C:H films with the thickness of ~50 nm were deposited on quartz substrates using the chemical vapor deposition of toluene vapor in glow discharge plasma. The nanogranulated silver film by 10 nm thickness was deposited on all a-C:H film by the thermal evaporation method at the same time. The optical density spectra and the surface morphology of Ag nanoparticles (NPs) by AFM as well as the PL spectra of a-C:H in the hybrid structures at the visible range and room temperature were obtained. It has been shown that PL intensity of wide-gap a-C:H in the hybrid structure increased fourfold but the narrow-gap film – sevenfold against the intensity of initial films at excitation wavelength 405 nm. The intensity of dipole and quadrupole mode peaks increased in the optical density spectra after annealing of the hybrid structures at 200 °C. This fact was connected with the form and size changes of Ag NPs. The blue shift of PL maximum to 498 nm and the twentyfold enhancement of PL intensity of the hybrid structure with the narrow-gap a-C:H was observed after annealing. The mechanism of plasmon-enhanced of a-C:H PL in hybrid structures with Ag NPs was discussed. Obtained results can find practice applications in both light-emitting devices and biosensor chip.

Optical tuning of plasmon-enhanced photoluminescence.

Photoluminescence (PL) can be enhanced and tuned with the assistance of surface plasmons. Traditional methods of generating tunable fluorophores are either of low efficiency or complicated with poor controllability. Here, we propose the optical tuning and enhancement of PL by modifying the plasmon modes, which shows unique advantages of generality, simplicity, and on-demand controllability. We adopted gold nanoparticles on a mirror as the plasmonic resonator, and responsive polymers as the spacers as well as the emitters in the nanogaps. By controlling the coating thickness of polymers, we can achieve tunable plasmon resonances as well as PL peaks with an enhancement factor up to ∼7000. Furthermore, we show the optical tuning of the plasmon resonances via laser irradiation which modifies the nanogaps. Thus, the PL peaks of the polymers shift accordingly with plasmon resonances. This tuning mechanism is based on plasmon-enhanced PL, which selectively enhances PL signals at different wavelengths. Such a plasmon-assisted PL selection by the optical tuning method provides new opportunities for photonic devices with applications of multiplex sensing and full colour displays.

Gap plasmon-enhanced photoluminescence of monolayer MoS2 in hybrid nanostructure**Project supported by the National Natural Science Foundation of China (Grant Nos. 61590932 and 11774333), the Anhui Initiative Project in Quantum Information Technologies, China (Grant No. AHY130300), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB24030600), the National Key Research and Development Program of China (Grant No.

Monolayer transition-metal dichalcogenides (TMDs) have attracted a lot of attention for their applications in optics and optoelectronics. Molybdenum disulfide (MoS2), as one of those important materials, has been widely investigated due to its direct band gap and photoluminescence (PL) in visible range. Owing to the fact that the monolayer MoS2 suffers low light absorption and emission, surface plasmon polaritons (SPPs) are used to enhance both the excitation and emission efficiencies. Here, we demonstrate that the PL of MoS2 sandwiched between 200-nm-diameter gold nanoparticle (AuNP) and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS2 sample. This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.

Plasmonic enhancement of photoluminescence from cadmium sulfide and lead sulfide quantum dots

Plasmonic core/shell nanoparticles Ag/SiO2 with different shell thicknesses were synthesized. Localized plasmon resonance was investigated by UV-vis spectroscopy. Arranged layers of plasmonic nanoparticles and quantum dots were obtained on a quartz substrate using a spin-coating technique. Plasmon-enhanced photoluminescence excited by 405 nm laser corresponding to the plasmon resonance was studied on CdS and PbS quantum dots structures. The possibilities of twofold and fourfold intensity increase are demonstrated for CdS and PbS quantum dots respectively.

Influence of Support Structure on the Ultraviolet Photoluminescence Enhancement from Graphene/ZnO Hybrid Structures

Novel application of graphene combined with light emitting materials has been proposed recently due to the plasmonic effects of graphene. Here, we report our investigations on the structural and optical properties of two graphene/ZnO hybrid structures that fabricated based on different ZnO supports. Plasmon-enhanced ultraviolet photoluminescence has been observed from both samples. The combined Raman and photoluminescence studies suggest a strong interaction between ZnO and graphene, which is affected by the surface structures of ZnO. Our results develop insights about the influence of ZnO supports on the PL enhancement and interfacial coupling in graphene/ZnO hybrid structures, which provides a reference for the design and fabrication of optoelectronic devices with high efficiency.

Photoluminescence of Fullerene C60 Thin Film in Plasmon-Coupled Monolayer of Au Nanoparticles – C 60 Film – Al Film Nanostructure

The plasmon-enhanced photoluminescence of fullerene C60 thin film has been studied to reveal the dependence of the magnitude of plasmonic field in coupled nanosystem monolayer of gold nanoparticles – fullerene C 60 film – aluminum film on the thickness of the fullerene spacer in the range of 10–95 nm. The non-monotonic dependence of the photoluminescence enhancement factor with minimum at the fullerene film thickness of 50 nm has been observed. Such dependence has been explained as the result of excitation of the propagating surface plasmon polaritons in aluminum film by the near field of localized surface plasmons of gold nanoparticles. The excitation of polaritons leads to additional radiative damping of plasmonic oscillations in gold nanoparticles that causes the decrease of the enhancement factor of the intensity of fullerene photoluminescence. Fifty nanometers is revealed to be the spacer thickness at which the most effective excitation of surface plasmon polaritons occurs.

Identifying Excitation and Emission Rate Contributions to Plasmon-Enhanced Photoluminescence from Monolayer MoS2 Using a Tapered Gold Nanoantenna

Single-element and periodic arrays of plasmonic nanoantennas have been used to enhance light–matter interactions in 2D materials to improve their suitability for optoelectronic devices. However, single nanoantennas with discrete resonances do not readily enable separation of enhancements in excitation and emission, each of which influences total Raman and photoluminescence (PL) enhancement. Here we use a single Au tapered plasmonic nanoantenna with optical resonances that extend above and below the band gap to observe a broad enhancement in PL of MoS2. The largest peak enhancement of ∼3.2 is observed at an antenna position between the position of maximum excitation-field enhancement and the position of maximum Purcell factor, indicating a contribution of both excitation and emission rate enhancements. In contrast, the peak Raman enhancement occurs at the position of the excitation-field maximum because it is only dependent on the enhancement of the electric field. This independent determination of excitat...