Plasmon Resonance Of Nanoparticles Research Articles

Optical properties and thermal stability of AlCrON-based multilayer solar selective absorbing coating for high temperature applications

A multilayer coating comprising Cr as IR reflector, alternative AlCrN/AlCrON as absorber and AlCrO as anti-reflective layer has been designed and deposited on stainless-steel substrate by cathodic arc ion plating. It was found that the selectivity (α/ε) of multilayer coating was increased from 0.919/0.128 to 0.928/0.105 after annealing at 550 °C in vacuum for 2000 h. Microstructural analysis revealed the formation of nanocrystalline/amorphous composite structures in the AlCrN/AlCrON absorbers and AlCrO anti-reflective layer, which was beneficial to improve the thermal tolerance of the multilayer coating by restraining nanoparticles agglomeration and interface degradation. The enhancement in selectivity after vacuum annealing was ascribed to the partial recrystallization of the amorphous matrices, resulting in the formation of nitride nanoparticles, which can promote the intrinsic absorption due to the increase of optical path. However, the multilayer coating destabilized when annealed at 550 °C in air for 2000 h. Based on the microstructural characterization, the corresponding failure mechanism was attributed to the element migration between adjacent sublayers, structural relaxation of the amorphous matrix, and surface solute atoms segregation induced oxidation and coalescence of nanoparticles, which degenerated the intrinsic absorption and localized surface plasmon resonance of nanoparticles in AlCrN and AlCrON absorbers.

Plasmon‐Induced Pyro‐Phototronic Effect Enhancement in Self‐Powered UV–Vis Detection with a ZnO/CuO p–n Junction Device

AbstractIt is important to detect light of low power density sensitively and fast for the application of optical communication, environmental monitoring, astronomy, and national securities. However, ZnO‐based photodetectors exhibit long decay time owing to the persistent photoconductivity (PPC) and are hard to detect light with low power density efficiently. Here, a practical strategy is utilized to improve the performance of ZnO‐based photodetectors by coupling the pyroelectric effect of ZnO with localized surface plasmon resonance (LSPR) of Au nanoparticles subtly. Hence, a self‐powered photodetector is demonstrated, which is integrated with ZnO/CuO core–shell nanorods and Au nanoparticles to detect UV to vis light. This self‐powered photodetector achieves fast and sensitive detection of UV when power density is 68 nW cm−2. The performance is significantly improved than the photodetectors without Au nanoparticles. The optimal responsivity and detectivity under the same power density of UV at 325 nm are 1.4 × 10−4 A W−1 and 3.3 × 1011 Jones. Response/recovery time is remarkably shortened to ≈10 ms. The results indicate that the material configurations and design concept make the device applicable for self‐powered, high‐performance photodetectors, and provide further promoted understanding of LSPR enhanced performance of photodetectors.

Plasmonic Bismuth Nanoparticles: Thiolate Pyrolysis Synthesis, Size-Dependent LSPR Property, and Their Oxidation Behavior.

Plasmonics, especially the localized surface plasmon resonance (LSPR) in non-noble metal bismuth nanoparticles (Bi NPs), and its spectral features and applications have stimulated increasing research interest in recent years. However, the lack of mature methods to prepare Bi NPs with a well-controlled size and/or shape significantly limits the experimental investigations concerning the LSPR optical properties. Herein, we realize the size-tunable synthesis of nearly monodisperse spherical Bi NPs through a thiolate pyrolysis reaction in solution. The instantaneous thermolysis of a layered molecular intermediate, bismuth dodecanethiolate [Bi(SC12H25)3], results in a classical LaMer mechanism for the nucleation and growth of Bi NPs, allowing for a precise size control from 65 to 205 nm in the average diameter. The diameter tunability enables a systematic study on the size dependence of LSPR optical properties of Bi NPs, and we observe rich ultraviolet-visible-near-infrared spectral responses arising from the LSPR absorption and scattering of Bi NPs as their size varies, which will greatly benefit the light harvesting and manipulation in the solar spectrum. Furthermore, we find that a complete oxidation occurs to Bi NPs under air flow at the temperature when they melt and accordingly generate metastable tetragonal-phase β-Bi2O3 NPs that show an optical band gap of 2.15 eV and interesting temperature-dependent β → α → δ → (γ + β) polymorphic transitions.

Enhanced surface plasmon resonance in gold nanoparticles dewetted on monolayer hexagonal boron nitride

In this paper, the effect of dewetted gold nanoparticles (AuNPs) on hexagonal boron nitride (hBN) is discussed along with the changes in surface plasmon resonance (SPR). Au is sputtered on monolayer hBN/SiO2/Si substrate for a varied duration and subjected to thermal annealing. Monolayer hBN is verified by spectroscopic ellipsometry using the Tauc–Lorentz model, while the AuNPs are modeled using a combination of Gauss, Cody–Lorentz, and Tanguy dispersion laws. Sputtering of Au on hBN/SiO2/Si results in a film-like layer compared to the one on SiO2/Si. Before annealing, the improved uniformity of Au on hBN/SiO2/Si diminished the SPR wavelength, [Formula: see text], when the sputter duration exceeded 30 s, much sooner compared to 120 s from the one on SiO2/Si. After annealing, the [Formula: see text] is vibrant for all samples around 2.3 eV. Au dewetted more on hBN due to higher surface tension. Large dewetted AuNPs supported by hBN result in higher photon extinction at [Formula: see text]. The longest sputter duration of 120 s on hBN/SiO2/Si (mean size 53 nm) exhibited an 11.2% higher extinction coefficient compared to the one on SiO2/Si (mean size 39.6 nm). Findings support the advantages of preparing plasmonic AuNPs by dewetting on monolayer hBN.

Introducing DNA Nanosensor to Undergraduate Students: Rapid Non-Cross-Linking Aggregation of DNA-Functionalized Gold Nanoparticles for Colorimetric DNA Assay

Demonstration of a colorimetric approach for nucleic acid detection represents an attractive educational experiment for chemistry undergraduate students in the time of coronavirus pandemic. Herein, a rapid and vivid detection method that visualizes the presence of a specific DNA sequence is described. The plasmon resonance of gold nanoparticles (AuNPs) (∼20 nm in diameter) endows a red color to DNA-functionalized gold nanoparticles (DNA-AuNPs) in a colloidal solution. Simply upon addition of a sample containing the complementary DNA sequence, the DNA-AuNPs dispersed in a strong ionic solution can spontaneously aggregate in minutes and turn to be purple in color, which can be detected using UV–visible spectroscopy as well as the naked eye. In contrast, the DNA-AuNPs remain highly dispersed as a reddish colloid even at high ionic strength when the DNA sequence is terminally mismatched or overhung. According to the teaching experience, this DNA testing experiment can be accomplished by students in pairs or groups under instruction in a three-day lab session. Given the rapid and fail-proof DNA testing, the testing method is also well-suited for hands-on introduction of analytical chemistry and nanotechnology to chemistry freshman and high school students.

Ultrasensitive prostate specific antigen monitoring based on electrochemiluminescent immunesystem with synergistic signal amplification effect of resonance energy transfer coupling with K2S2O8-H2O2 dual coreactants

• The synergistic effect of coupling dual coreactants with the surface plasmon resonance of AgNPs enhancement was used as an effective signal amplification strategy. • OH • arising in the process was able to induce the decomposition of S 2 O 8 2− into SO 4 • − resulting in a vigorous ECL enhancement. • The amplified ECL immunosensor was fabricated for highly-sensitive detection of PSA. • The sensing system provides an alternative charming method for other biomolecules assays. In this work, an effective signal amplification strategy was used for the fabrication of the ultrasensitive sandwich-typed electrochemiluminescence (ECL) immunosensing platform. The combining of K 2 S 2 O 8 -H 2 O 2 dual coreactants with the localized surface plasmon resonance of silver nanoparticles (AgNPs) resulted in the remarkable increase of ECL response. Noticeably, because of the perfect overlap between the plasmon spectra of AgNPs and the ECL emission spectra of graphitic carbon nitride quantum dots (g-CNQDs), a plasmon-enhanced ECL phenomenon was proved in g-CNQDs/AgNPs system result from high efficient energy transfer. Besides, the ECL signal of the ECL immunosensor was greatly improved in the presence of K 2 S 2 O 8 -H 2 O 2 dual coreactants. Consequently, this synergistic amplified ECL sensing platform was applied for the specific prostate specific antigen (PSA) analysis. Under the optimum conditions, the immunoassay strategy demonstrated excellent sensing performance with a wide linear concentration of PSA from 1.0 × 10 − 5 ng mL −1 to 500 ng mL −1 and a detection limit of 0.0046 pg mL −1 (S/N = 3). Considering the favorable analytical feedback in actual serum samples assay, the developed strategy indicated an enormous potential for biomarkers analysis.

Effect of Geometrical Properties on Localized Surface Plasmon Resonance of Gold Nanoparticles

This work reportson plasmonic effects (i.e light scattering and absorption properties) induced by two different gold nanoparticles (AuNPs)-shaped: spherical particle and triangular particle. The scattering cross-section and electric field profiles have been investigated by using theboundary element method (MNPBEM toolbox). Two configurations: the isolated AuNPand the coupledtwo-gold NPsystem have been considered to evaluate the localized surface plasmon resonance (LSPR) in eithersingle or coupled AuNPstructures. The effect of the surrounding medium on the scattering behavior of the NPs has also been examined. Then the dependence of “hotspot” intensity on the distance between two NPs has been recognized by mapping the electric field profile. The obtained results can be used as the guidelines for synthesizing AuNP structures to employ LSPR for sensing or other applications.

Photodegradation of acenaphthylene over plasmonic Ag/Ag3PO4 nanopolyhedrons synthesized via in-situ reduction

We report a simple strategy to synthesize the Ag3PO4 nanopolyhedrons with regular morphology and uniform size under mild conditions. The photocatalytic properties of the composite were optimized by adjusting the content of Ag nanoparticles. The as-prepared photocatalysts were characterized and the photocatalytic performances were evaluated by the degradation of acenaphthylene (ANY) under visible-light illumination. The surface plasmon resonance (SPR) of appropriate Ag nanoparticles was generated on surface under visible light irradiation, which enhanced the absorption and utilization of visible light. At the same time, the conductivity of Ag promoted the separation and transfer of photogenerated carriers, provided active sites for the reaction, and enhanced the photocatalytic degradation efficiency through the generation of active species. As a result, the optimized composite exhibited enhanced visible-light photocatalytic activity of 0.03512 min−1 and higher removal rate of 97.3% for ANY (4 times and 1.8 times higher than that of pristine Ag3PO4, respectively), more photogenerated active species (h+ and •O2–) and relatively high stability (4 times of cycle experiments). In addition, the possible degradation pathway of ANY was proposed. The work of this paper has a crucial guiding significance for the working principle and design direction of silver semiconductor composite photocatalysts with surface plasmon effect.

Functionalized UIO-66@Ag nanoparticles substrate for rapid and ultrasensitive SERS detection of di-(2-ethylhexyl) phthalate in plastics

The rapid and sensitive detection of di-(2-ethylhexyl) phthalate (DEHP) in plastics is of great significance because of its toxicity and persistent contamination. Surface-enhanced Raman scattering (SERS) technology makes the detection of DEHP fast and convenient, but it suffers some disadvantages such as the weak adsorption capacity of target molecules, low efficiency and limited sensitivity. Herein, octahedral UIO-66 of metal-organic frameworks (MOFs) was successfully synthesized, followed by the growth of silver nanoparticles on its surface (UIO-66@Ag NPs) to form a composite SERS substrate to detect DEHP. Taking advantages of large surface area and high porosity of UIO-66, the prepared UIO-66@Ag NPs substrate not only could reduce the aggregation and increase the “hot spots” formed by localized surface plasmon resonance (LSPR) of Ag nanoparticles, but also possess good adsorption capacity for DEHP. The SERS-enhanced mechanism was fundamentally discussed for UIO-66@Ag NPs substrate, and the enhancement factor (EF) of SERS signal for DEHP detection was calculated about 1.1 × 107. The fabricated UIO-66@Ag NPs SERS substrate could realize quantitatively non-destructive determination of DEHP ranging from 10−4 to 10−11 mol/L (R2 = 0.9950) with very low detection limit of 3 × 10−12 mol/L. Meanwhile, the UIO-66@Ag NPs substrate exhibited outstanding reproducibility and stability, and was successfully applied to detect DEHP in real plastic particles with satisfactory recoveries of 81.9–110.1%. These results demonstrated that this method offered a suitable path for the research of advanced SERS sensing materials to achieve monitoring of DEHP in plastics.

Photogated Coordination Switching of Silver Nanoparticles for Reversible Coloration/Discoloration of Hydrogel

AbstractHydrogels remain challenging for the reversible high‐resolution coloration/discoloration in response to external stimuli. Herein, a photogated coordination‐switching mechanism is proposed to alter the localized surface plasmon resonance of silver nanoparticles (AgNPs) inside a hydrogel network, which enables the reversible color change. The hydrogel is synthesized by free‐radical crosslinking of N,N'‐bisacrylylcystamine (BACA), sodium p‐styrenesulfonate (NASS), and acrylamide (Am) in the presence of AgNPs. Upon light irradiation at λ = 400 nm (300 mW cm−2), the AgNPs selectively coordinate with the disulfide bond of BACA to result in a reddish‐brown hydrogel in 30 s. In dark condition, this coordinating effect is replaced by the sulfonate of NASS and AgNPs, which brings the hydrogel into gray white. Such a photogated coordination‐switching mechanism is a physical process that enables the coloration/discoloration cycles without apparent reduction in the resolution. By means of a high‐precision mask, it allows writing, storing, and erasing of complicated information at the hydrogel surface, showing a great potential in informatics, cryptology, and security areas.

Measuring of metanephrine by UV-Vis peak of surface absorption Plasmon resonance of silver nanoparticles by response surface methodology

A simple and low-cost spectrophotometry method was proposed based on resonance Plasmon peak of silver nanoparticles for measurement of metanephrine(MN) drug. This method was based on reducing property of metanephrine and it was founded that this compound reduces silver ions in presence of polyvidone (PVP) as stabilizer compound. In this condition the formed silver nanoparticles show a localized surface plasmon resonance (LSPR) peak of about 423 nm. The resulted nano-particles were analyzed by transmission electron microscope (TEM) technique and nanoparticles size was estimated to be maximum of 200nm. Furthermore, realized that the absorption of solution depends on concentration of metanephrine and the maximum of absorption was found at 〖AgNO〗_3 concentration of 1.53 mM, NaOH concentration of 4.10 mM, 〖NH〗_3 concentration of 2.51 mM and 1.15 ml of PVP. Also, the proposed method showed a good linear relationship than MN concentration in the range of 2.5-20 µM and limit of detection was obtained as 0.6 µM for metanephrine. Finally, this method was used for measuring epinephrine in real samples and the acceptable results were obtained.

Zirconium Nitride: Optical Properties of an Emerging Intermetallic for Plasmonic Applications

Finding new plasmonic materials with prominent optical properties and unique physical and chemical characteristics, which are merits of traditional gold and silver, is of great interest to many applications. This work uses a series of powerful numerical methods, such as density functional theory (DFT) and electromagnetic modeling approaches, to predict the plasmonic response of a mechanically well‐known material, zirconium nitride (ZrN). DFT first delivers an electronic analysis and optical dispersion data between 1 and 8 eV, experimentally verified in the lower energy regime (), and extremely valuable for any subsequent optical modeling. Subsequent electromagnetic modeling steps, including the transfer matrix method (TMM) and Mie theory, demonstrate the excitation of surface plasmon polaritons and localized surface plasmon resonances in ZrN thin films and nanoparticles. Furthermore, the finite‐difference time‐domain (FDTD) method exhibits the excitation of distinct electric (plasmon) and magnetic (LC) resonances in a periodic array of u‐shaped ZrN split‐ring resonators (SRRs). The findings showcase an optical behavior comparable with structures made from noble metals such as gold and silver and support the introduction of ZrN as a new and appropriate candidate for plasmonic applications, specifically in technological applications where optical and mechanical properties are of simultaneous concern.

Utilization of Localized Surface Plasmon Resonance of Silver Nanoparticles for the Spectrofluorimetric Estimation of Oxymetazoline in Dosage Forms: Application to Aqueous Humor.

A simple, novel, cost-effective and highly sensitive spectrofluorimetric method was developed for estimation of the nasal decongestant oxymetazoline (OMZ) whether per se or in its pharmaceutical preparations using colloidal silver nanoparticles (AgNPs). The method is based on the high catalytic potential activity of AgNPs on the fluorescence intensity of OMZ leading to 12-fold increase in its fluorescence intensity. The response was linear over the range of 20.0 to 700.0ng/mL with lower detection limit of 5.0ng/mL and limit of quantification of 14.0ng/mL. The proposed method was applied to the assay of commercial nasal drops, nasal spray and synthetic aqueous humor. Interference likely to be encountered from co-administered drugs was studied. The developed method was optimized and validated as per International Council of Harmonization (ICH). An explanation for the drug-AgNPs interaction was proposed.

Revealing the Hemispherical Shielding Effect of SiO2@Ag Composite Nanospheres to Improve the Surface Enhanced Raman Scattering Performance.

Many studies widely used SiO2@Ag composite nanospheres for surface enhanced Raman scattering (SERS), which mainly contributes to electromagnetic enhancement. In addition to experiments, previous simulations mostly adopted a two-dimensional model in SERS research, resulting in the three-dimensional information being folded and masked. In this paper, we adopted the three-dimensional model to simulate the electric field distribution of SiO2@Ag composite nanospheres. It is found that when the Ag nanoparticles are distributed densely on the surface of SiO2 nanospheres, light cannot pass through the upper hemisphere due to the local surface plasmon resonance (LSPR) of the Ag nanoparticles, resulting in the upper hemisphere shielding effect; and if there are no Ag nanoparticles distributed densely on the surface of SiO2 nanospheres, the strong LSPR cannot be formed, so the incident light will be guided downward through the whispering gallery mode of the spherical structure. At the same time, we designed relevant experiments to synthesize SiO2@Ag composite nanosphere as SERS substrate and used Rhodamine 6G as a probe molecule to study its SERS performance. This design achieved a significant SERS effect, and is very consistent with our simulation results.

Plasmonic Au Nanoparticle Arrays for Monitoring Photopolymerization at the Nanoscale

The localized surface plasmon resonance (LSPR) of Au nanoparticles (NPs) was used to monitor photopolymerization at the nanoscale by in situ monitoring the optical response of AuNPs during the light-induced polymerization process. To show the interest of this approach, two configurations were used, which correspond to a resonant and a nonresonant excitation regime between the photopolymer and the AuNPs used as nanoprobes. We show that not only this method enables the progress monitoring of the photopolymerization reaction at the nanometric scale but also can highlight the near-field coupling effect responsible for the acceleration of the photoinduced reaction. This methodology appears very interesting to study the photoinduced nanofabrication processes of metal/polymer hybrid nanoparticles and more globally to study the photopolymerization reactions at the nanometric scale.

Localized surface plasmon resonance enhanced electrochemical kinetics and product selectivity in aprotic Li–O2 batteries

Lithium–oxygen (Li-O2) batteries have the potential needed for portable electronic devices and electric vehicles, but the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes hinder the practical implementation. Here, we propose that the localized surface plasmon resonance (LSPR) of silver nanoparticles (Ag NPs) induced the plasmonic thermal and hot electron effects can simultaneously enhance reaction kinetics of ORR, OER, reduce the reaction activation energy and promote the discharge product selectivity to mitigate unfavourable side reactions, which greatly improves the catalytic performance of Ag NPs. Furthermore, we also calculated the photochemical conversion coefficient and the quantitative contribution of the ratio of two effects towards the catalytic activity. Notably, by accelerating both oxygen reduction and evolution reactions, the discharge voltage is significantly increased to 3.2174 V, which is surpass the thermodynamic limit of 2.96 V, and the charge voltage is reduced to 3.2487 V (overpotential of 0.0331 V), resulting in a high round-trip efficiency of 99%. The concept can be extended to other types of batteries, such as Zn-air battery, thus contributing to the development of advanced energy storage systems.

Enhancement of Scattering and Near Field of TiO2-Au Nanohybrids Using a Silver Resonator for Efficient Plasmonic Photocatalysis.

Recently, localized surface plasmon resonances (SPRs) of metallic nanoparticles (NPs) have been widely used to construct plasmonic nanohybrids for heterogeneous photocatalysis. For example, the combination of plasmonic Au NPs and TiO2 provides pure TiO2 visible-light activity. The SPR effect induces an electric field and consequently enhances light scattering and absorption, favoring the transfer of photon energy to hot carriers for catalytic reactions. Numerous approaches have been dedicated to the improvement of SPR absorption in photocatalysts. Here, we have designed a core@shell-satellite nanohybrid catalyst whereby an Ag NP core, as a plasmonic resonator featuring unique dual functions of strong scattering and near-field enhancement, is encapsulated by SiO2 and TiO2 layers in sequence, with Au NPs on the outer surface, Ag@SiO2@TiO2-Au, for efficient plasmonic photocatalysis. By varying the size and number of Ag NP cores, the Au SPR can be tailored over the visible and near-infrared spectral region to reabsorb the scattered photons. In the presence of the Ag core, the incident light is efficiently confined in the reaction suspension by undergoing multiple scattering, thus leading to an increase of the optical path to the photocatalysis. Moreover, using numerical analysis and experimental verifications, we demonstrate that the Ag core also induces a strong near-field enhancement at the Au-TiO2 interface via SPR coupling with Au. Consequently, the activity of the TiO2-Au plasmonic photocatalyst is significantly enhanced, resulting in a high H2 production rate under visible light. Thus, the design of a single structural unit with strong scattering and field enhancement, induced by a plasmonic resonator, is a highly effective strategy to boost photocatalytic activity.

Towards applicable photoacoustic micro-fluidic pumps: Tunable excitation wavelength and improved stability by fabrication of Ag-Au alloying nanoparticles

Photoacoustic micro-fluidic pumps (PMPs) based on localized surface plasmon resonance (LSPR) of nanoparticles (NPs) can convert photo energy into kinetic energy of fluidic jetting therefore attracted considerable attentions in microfluidics and optofluidics. In this work, PMPs are fabricated using Ag-Au alloy NPs. Through solid-state-dewetting, alloy NPs are prepared of variable component ratios for tunable LSPR absorption between 440 and 530 nm. The relationship between NP morphology and optical properties are studied with the assistant of finite-difference time-domain (FDTD) simulation. Photoacoustic jets are observed through the excitation of both 450 and 532 nm lasers. Noticeably, with 450 nm laser, long lasting jets over 1 h are excited on Ag0.9Au0.1, which sharply contrast to the duration within 1 min on Ag0.2Au0.8 NPs with 532 nm laser, indicating the importance of material selection in performance improvement. Further investigation on jetting stability is performed according to the morphological evolution by laser striking, suggesting the enhanced stability can be related to the increased melting-point and thermal-stability of alloys.

Photonic bandgap influence on the SERS effect in metal-dielectric colloidal crystals optical fiber probe

This paper promotes a simple surface-enhanced Raman spectroscopy (SERS) substrate based on metal-dielectric colloidal crystal (MDCC) consisting in 3D self-assembled colloidal of polystyrene nanospheres (PSNPs) doped with gold nanoparticles (AuNPs). We demonstrate that the overlapping of localized surface plasmon resonance (LSPR) of noble metallic nanoparticles and photonic bandgap (PBG) of colloidal crystal can be tuned for the benefit of SERS performance. To tune the photonic bandgap, PSNPs with different diameter were selected, 242 nm and 300 nm, respectively, combined with AuNPs of about 23.3 nm. We found that the SERS signal can be enhanced more than 30 % when the laser excitation wavelength falls on the high wavelength edge of the photonic band gap. Moreover, the MDCCs have been fabricated by top-down methodology directly onto optical fiber providing efficient SERS-on-tip probes. The SERS features of the fiber probes in optrode configurations have been investigated by using different concentration of Rodamine (R6G) as molecular reporter. In all investigated cases, SERS activities is very well detectable even in case of R6G concentration of 1μM and analytical enhancement factors, AEF, of up to 3300 are obtained.

Control of localized surface plasmon resonance of Ag nanoparticles by changing its size and morphology

Ag thin-films with thicknesses of 5, 10, 15, 20, and 25 nm are deposited by thermal vacuum evaporation, and the obtained films are subsequently annealed at 400 °C for 1 h to form the Ag nanoparticles (NPs). The averaged diameters of the resultant Ag NPs are increased from 50 to 300 nm as increasing the initial Ag deposition thickness, according to the morphological observation using scanning electron microscopy (SEM). The significant red-shift of the extinction peak depending on the particle size of the Ag NPs, which can be assigned to the localized surface plasmon resonance of the Ag NPs. The organic emitter, tris(8-hydroxyquinolinato)aluminum (Alq3) film is overcoated on the Ag NPs. About 4-fold enhancement of the photoluminescence of Alq3 was observed in combination with the larger size Ag NPs fabricated from the 15–25 nm thick Ag films, which can be applied for the improvement of the light-extraction efficiency of the organic light-emitting devices.