Strong Localized Surface Plasmon Resonance Research Articles

Metallic Ti3O5 hierarchical porous microspheres with an enhanced photothermal property.

γ-Ti3O5 is one kind of prominent non-stoichiometric metal oxide due to its intriguing ability in electric and electrochemical behaviors. This work reports another attractive property of γ-Ti3O5 hierarchical porous microspheres, the extremely effective photothermal property with a high photothermal conversion efficiency. Theory and experimental results indicate that γ-Ti3O5 hierarchical porous microspheres possess metallic features and display very strong localized surface plasma resonance effects over the visible and near-infrared region. Under simulated sunlight or near infrared light, the metallic γ-Ti3O5 exhibits a photothermal conversion efficiency of up to 65.29%. Under irradiation by a near-infrared laser with a wavelength of 808 nm, the γ-Ti3O5 hierarchical porous microspheres can significantly inhibit cancer cell viability in vitro and disrupt tumor tissue growth in vivo in a short period. In vitro and in vivo toxicity experiments demonstrate that it has good biocompatibility. The ultrahigh photothermal conversion efficiency and biocompatibility make the γ-Ti3O5 very attractive for technological uses in photothermal therapy, solar energy utilization, and infrared light detection and so on.

Plasmonic metal carbide SERS chips

Plasmonic tungsten carbide, niobium carbide, titanium carbide and molybdenum carbide chips possess remarkable SERS activity.

Efficiency improvement in solution-processed multilayered phosphorescent white organic light emitting diodes by silica coated silver nanocubes

Localized surface plasmon resonance (LSPR) effect of metal nanoparticles (MNs) has been widely applied in organic light-emitting diodes (OLEDs) to improve the radiation of excitons. The LSPR wavelength and intensity of MNs and the coupling between MNs and excitons greatly affect the LSPR effect on exciton radiation. In this work, silica coated silver nanocubes (Ag@SiO<sub>2</sub> NCs) were doped in the electron transport layer (ETL) of a solution-processed multilayered white OLED (WOLED). Due to the sharp edges and corners, Ag NCs have strong LSPR effect and can effectively enhance the radiation of nearby excitons. With an appropriate concentration of Ag@SiO<sub>2</sub> NCs, the WOLED achieved two fold improvement in the current efficiency comparing with the control device without Ag@SiO<sub>2</sub> NCs incorporated. The working mechanism of the Ag@SiO<sub>2</sub> NCs based WOLED was investigated in detail. For the solution-processed OLED, excitons usually form and recombine near the interface of emission layer and electron transport layer (EML/ETL) because the commonly used host material (such as polyvinylcarbazole, PVK) has the unipolar hole transport property. So the Ag@SiO<sub>2</sub> NCs in ETL greatly enhanced the radiation of the excitons located near the EML/ETL interface, which mostly contributed to the performance enhancement of the Ag@SiO<sub>2</sub> NCs based WOLED. Study on a group of devices with Ag@SiO<sub>2</sub> NCs doped in different locations indicated that Ag@SiO<sub>2</sub> NCs in ETL showed more effective LSPR effect than those in hole injection layer. Electroluminescence and photoluminescence spectra of the WOLEDs declared that the Ag@SiO<sub>2</sub> NCs simultaneously improved the radiation intensities of the blue and yellow excitons and helped the WOLED maintain the good chromaticity stability, which was mainly attributed to the wide LSPR wavelength range (450–650 nm) of the Ag@SiO<sub>2</sub> NCs. The SiO<sub>2</sub> coating layer of the Ag@SiO<sub>2</sub> NCs played the important role in the LSPR enhanced emission. On the one hand, it formed an appropriated distance between the Ag NCs and the extions, helping to generate the strong coupling between them. On the other hand, it suppressed the effect of Ag NCs on charge trapping, keeping the stability of the carrier transport in the device. Our research demonstrate MNs can effectively improve the performance of OLEDs by carefully designing the device structure.

Wide-Angle Polarization-Independent Ultra-Broadband Absorber from Visible to Infrared.

We theoretically proposed and numerically analyzed a polarization-independent, wide-angle, and ultra-broadband absorber based on a multi-layer metasurface. The numerical simulation results showed that the average absorption rates were more than 97.2% covering the broad wavelength of 400~6000 nm (from visible light to mid-infrared light) and an absorption peak was 99.99%, whatever the polarization angle was changed from 0° to 90°. Also, as the incidence angle was swept from 0° to 55°, the absorption performance had no apparent change over the wavelength ranges of 400 to 6000 nm. We proved that the proposed metasurface structure was obviously advantageous to achieve impedance matching between the absorber and the free space as compared with conventionally continuous planar-film structures. The broadband and high absorption resulted from the strong localized surface plasmon resonance and superposition of resonant frequencies. As expectable the proposed absorber structure will hold great potential in plasmonic light harvesting, photodetector applications, thermal emitters and infrared cloaking.

Enhanced efficiency in dye-sensitized solar cell by localized surface plasmon resonance effect of gold nanoparticles

Strong localized surface plasmon resonance (LSPR) field, which is generated from gold nanoparticles, may enhance photons absorption of dyes in dye-sensitized solar cells (DSSCs), resulting in the improvement of their power conversion efficiency (PCE). In this paper, we report the incorporation of oleylamine capped gold nanoparticles (AuOA NPs) into the N-719 dye layer in DSSCs. The cells were prepared by varying the weight percentage of AuOA NPs with respect to the dye weight in dye solutions. The dye solutions containing 1.44[Formula: see text]wt.%, 1.92[Formula: see text]wt.% and 2.4[Formula: see text]wt.% of AuOA NPs exhibited an enhancement in their absorption spectra in the UV-Visible range, which may be the result of the excitation of localized SPR. The [Formula: see text] characteristics of those DSSCs show an enhancement in their photocurrent along with their PCE, from 4.18% to 5.14% for the cells made from the dye solutions without AuOA and with addition of 2.4[Formula: see text]wt.% of AuOA, respectively. This improvement is due to the enhancement of light absorption and hence charge carrier generation by the Plasmonic wave generated by AuOA NPs through the LSPR phenomenon.

Gold Triangular Nanoplates Based Single-Particle Dark-Field Microscopy Assay of Pyrophosphate.

Owing to the sharp edge-enhanced electric field, gold triangular nanoplates (AuNPLs) exhibit strong localized surface plasmon resonance (LSPR) scattering and display as red spots with high intensity and narrow distribution under dark-field microscopy (DFM), based on which sensitive sensing applications could be developed. As a concept of proof, the inhibition effects of pyrophosphate (PPi) against the etching of AuNPLs based on Cu2+ and I- mediated is dynamically monitored. The etching proceeding of AuNPLs by copper ions and iodide ions leads to the gradually blue-shifted LSPR scattering color of AuNPLs under DFM from the original red to green, accompanied by the reduced LSPR scattering intensity. As a result of the strong affinity of PPi to copper ions, the presence of PPi makes the etching process greatly suppressed, thereby achieving sensitive detection of the PPi.

Improved localized surface plasmon resonance responses of multi-metallic Ag/Pt/Au/Pd nanostructures: systematic study on the fabrication mechanism and localized surface plasmon resonance properties by solid-state dewetting

Multi-metallic nanoparticles (NPs) can offer dynamic and tunable localized surface plasmon resonance (LSPR) properties that are suitable for various catalysis, sensing and energy harvesting applications due to the wide range of tunability and applicability. In this work, the systematic fabrication and improved LSPR characteristics of multi-metallic alloy NP arrays are demonstrated based on the solid-state dewetting (SSD) of multi-layers of Ag/Pt/Au/Pd on sapphire (0001). The evolution of surface NPs in terms of configurational and elemental specifications yields vary strong and dynamic LSPR bands in the UV and VIS wavelengths based on the excitation of various plasmonic modes, i.e. dipolar (DR), quadrupolar (QR), multipolar (MR) and higher order (HO) bands, which is further exploited by the finite difference time domain simulations. Through the systematic control of multi-layer thickness, layer ratio and growth conditions, various nanostructures such as voided nanoclusters, network-like NPs and isolated semispherical NPs are obtained, which are unique in terms of morphology and elemental composition at each stage of dewetting process. The growth mechanism of multi-metallic alloy NP arrays is proposed based on the temperature driven thermal diffusion, alloying, Rayleigh-like instability and energy minimization mechanisms. Due to the subsequent sublimation of Ag atoms at above 650 °C, a sharp alteration in the elemental and morphological characteristics is demonstrated. In specific, the high percentage of Ag alloy NPs exhibits strong LSPR bands and gradually weakened along with the Ag sublimation. At the same time, however, the alloy or mono-metallic NPs without Ag still demonstrate much stronger LSPR bands as compared to the monometallic NPs by the SSD of pure films.

Improved LSPR Properties of Ag–Pt and Pt Nanoparticles: A Systematic Study on Various Configurations and Compositions of NPs via the Solid-State Dewetting of Ag–Pt Bilayers

The localized surface plasmon resonance (LSPR) of noble metal nanoparticles (NPs) has become an important research topic in various fields and can be systematically tuned to obtain the desired device performance through the appropriate structural and elemental modifications. In this research, the improved LSPR properties of Pt NPs and diverse configurations and compositions of Ag–Pt bimetallic alloy NPs were demonstrated on sapphire (0001) via the solid-state dewetting (SSD) of Ag–Pt bilayers. A strong and dynamic LSPR response in the ultraviolet (UV) and visible (VIS) regions was demonstrated depending on the elemental composition and surface morphology of the NPs, which is discussed along with finite difference time domain (FDTD) simulations. In comparison, the Ag–Pt NPs exhibited stronger LSPR excitation, whereas the Pt NPs showed a relatively weaker and broader response. Meanwhile, the Pt NPs fabricated in this study still demonstrated a much-enhanced LSPR response compared to previous studies on the solid-state dewetting of pure Pt films due to improvements in configuration, uniformity, and interparticle gaps. Various surface morphologies of NPs, such as connected nanoclusters, elongated NPs, and isolated spherical NPs, were obtained on the basis of alloying, diffusion, Rayleigh instability, and a surface minimization mechanism, which were different from those of pure Ag and Pt NPs in similar growth conditions. Particularly, one-step annealing of an Ag–Pt bilayer yielded Ag–Pt alloy NPs below 600 °C, which subsequently transformed into pure Pt NPs above 650 °C, in which the high diffusivity and high vapor pressure of Ag atoms significantly facilitated the overall growth process of the NPs.

Solid state dewetting of Ag/Pt bilayers for the stronger localized surface plasmon resonance (LSPR) properties: The dynamic control of surface morphology and elemental composition of AgPt and Pt nanostructures by the auxiliary Ag layer

The modification and control of localized surface plasmon resonance (LSPR) properties of metallic nanoparticles (NPs) has become a vigorous research focus in various fields due to its wide range of applicability in various applications, which can be achieved by the control of surface morphology and elemental composition. In this paper, various configurations and compositions of AgPt and Pt NPs are demonstrated by the solid state dewetting using an auxiliary Ag layer on sapphire (0001) along with their strong dynamic LSPR properties. By the systematic control of Ag/Pt bilayer thickness and temperature, the interconnected AgPt nanoclusters at low temperature (<600 °C) and well-isolated pure Pt NPs at higher temperature (>650 °C) are obtained based on the enhanced diffusion, alloying, surface energy minimization and Ag sublimation. A strong LSPR response in the UV and VIS region is exhibited by the AgPt and Pt NPs depending on the alteration of size, shape, uniformity and elemental compositions. In particular, the AgPt NPs show the stronger plasmonic responses and it gradually attenuates with the sublimation of Ag atoms which results in the development of Pt NPs. In comparison with the previous study on the pure Pt NPs on sapphire, the Pt NPs in this study are significantly improved in terms of shape, size and spacing, whose LSPR responses are much stronger and dynamic. The auxiliary diffusion enhancement by Ag atoms leads to the rapid dewetting of AgPt NPs while the Ag sublimation assists the evolution of well-developed Pt NPs due to the vacancy creation and removal of material during mass transport. The tunability of surface morphologies and LSPR properties of AgPt and Pt NPs are systematically demonstrated by the methodical control of Ag/Pt bilayer thickness.

Ultra-broadband photoresponse of localized surface plasmon resonance from Si-based pyramid structures

Structures capable of exciting localized surface plasmon resonance (LSPR) have been widely utilized to increase photoresponse in many photoactive devices. However, most LSPR can be induced in only a small spectral range and with particular polarization. Here, LSPR with ultra-broadband response is revealed. Light detection using such LSPR is also explored to exhibit a spectral range covering the visible to mid-infrared. The strong LSPR induced by the inverted pyramid array structure enables a Si-based Schottky photodetector to detect photons even with energy lower than the Schottky barrier height, leading to the experimental measurement covering from 300 to 2700 nm. Theoretical evaluation even predicts a response beyond 4000 nm.

Plasmonic Cu nanostructures in ZnO as hyperbolic metamaterial thin films

Plasmonic metals, such as Cu and Al, have been considered as potential low-loss alternatives for Au and Ag for photonic structures and devices. However, challenges remain in the fabrication and applications of Cu nanostructures, because of its easy oxidation issues. In this work, a new metamaterial structure of plasmonic Cu nanostructures embedded in a dielectric ZnO matrix has been designed and successfully fabricated using a one-step thin film growth method. The Cu–ZnO hybrid thin films present excellent epitaxial quality and exotic optical properties, such as strong localized surface plasmon resonance in the visible regime, and, highly anisotropic and hyperbolic optical response, revealed by angular dependent and polarization resolved reflectivity measurements. This hyperbolic plasmonic metamaterial via the metal-in-oxide matrix form combining low-loss plasmonic Cu nanostructures and extraordinary anisotropic optical properties could be used towards various nanophotonic applications, such as plasmonic solar energy devices and hyperlens.

Stretchable and Highly Sensitive Optical Strain Sensors for Human-Activity Monitoring and Healthcare.

Flexible and stretchable strain sensors are essential to developing smart wearable devices for monitoring human activities. Such sensors have been extensively exploited with various conductive materials and structures, which, however, are normally in need of complex manufacturing processes and confronted with the challenge to achieve both large stretchability and high sensitivity. Here, we report a simple and low-cost optical strategy for the design of stretchable strain sensors which are capable of measuring large strains of 100% with a low detection limit (±0.09%), a fast responsivity (<12 ms), and high reproducibility (over 6000 cycles). The optical strain sensor (OS2) is fabricated by assembling plasmonic gold nanoparticles (GNPs) in stretchable elastomer-based optical fibers, where a core/cladding structure with step-index configuration is adopted for light confinement. The stretchable, GNP-incorporated optical fiber shows strong localized surface plasmon resonance effects that enable sensitive and reversible detection of strain deformations with high linearity and negligible hysteresis. The unique mechanical and sensing properties of the OS2 enable its assembling into clothing or mounting on skin surfaces for monitoring various human activities from physiological signals as subtle as wrist pulses to large motions of joint bending and hand gestures. We further apply the OS2 for quantitative analysis of motor disorders such as Parkinson's disease and demonstrate its compatibility in strong electromagnetic interference environments during functional magnetic resonance imaging, showing great promises for diagnostics and assessments of motor neuron diseases in clinics.

RuPd Alloy Nanoparticles Supported on Plasmonic HxMoO3–y for Efficient Photocatalytic Reduction of p‐Nitrophenol

p‐Nitrophenol (PNP) has aroused much concern due to its high toxicity in industrial wastewater and drinking water. Herein, we designed a new plasmonic RuPd/HxMoO3–y catalyst synthesized by a simple impregnation method, followed by H2 atmosphere reduction. The synthesized RuPd/HxMoO3–y hybrid, having RuPd alloy nanoparticles (NPs) anchored on HxMoO3–y, namely hydrogen‐doped molybdenum oxide support, shows a strong localized surface plasmon resonance (LSPR) absorption peak at around 639 nm. Photocatalytic activity of Ru/HxMoO3–y hybrid for the reduction of PNP to p‐aminophenol (PAP) under visible light irradiation can be dramatically improved by alloying with Pd atoms. More importantly, a reasonable mechanism for PNP reduction is proposed. We find that synergetic effect between HxMoO3–y and RuPd alloy NPs of RuPd/HxMoO3–y plays a vital role in photocatalytic reduction, in which RuPd alloy NPs act as the active species and plasmonic HxMoO3–y acts as electron‐donation centre.

Construction of Sensitive Surface‐Enhanced Raman Spectroscopy Chip with Sub‐Nanometer WO3−x Nanowire‐Based Superstructures for Multicomponent Detection

AbstractExploring nonmetallic plasmonic materials is desirable yet challenging. For a long time, free‐plasmonic semiconductor is difficult to be used in high‐sensitive surface‐enhanced Raman spectrum (SERS) due to poor enhanced factor and high‐fluorescent background. Herein, it is reported that a nonmetallic plasmonic SERS chip, constructed with a highly ordered sub 1 nm WO3−x nanowire‐based superstructure, shows multicomponent detection capability. The densely arranged nanowires enable a strong localized surface plasmon resonance due to the high charge carriers' density induced by oxygen vacancies in the nanowires. In addition to the usual charge‐transfer enhancement, such nonmetallic WO3−x displays a unusual dramatic plasmon‐enhanced SERS sensing performance with a detection limit of 10−10 m and a maximum Raman enhanced factor of 8.3 × 107. The substrate fluorescence signals are efficiently quenched, making the SERS spectra more distinguishable. More importantly, the prepared WO3−x SERS chip through micro–nano printing realizes the separation and detection of multicomponents simultaneously.

Nanotip-assisted photoreduction of silver nanostructures on chemically patterned ferroelectric crystals for surface enhanced Raman scattering

Nanotips made of metal and semiconductor have been widely utilized in versatile applications to strengthen the electric field through lightning rod effect and localized surface plasmon resonance (LSPR) effect. Here, we present the utilization of ferroelectric nanotips to assist photoreduction of silver nanostructures for surface enhanced Raman scattering (SERS). Ferroelectric nanotips with spontaneous polarization posses the unique feature of producing the permanent electrostatic field without requiring external excitation, which differs from the present nanotips requiring electrical and optical excitation. The enhanced electrostatic field promotes the formation of silver nanoparticles by reducing the effect of Stern layer and accelerating the movement of photoelectrons and silver ions to the template surface. Experimental results show that sharp ferroelectric nanotips facilitate the formation of large-diameter nanoparticles with strong LSPR action. Compared to the conventional ferroelectric templates, the SERS substrates using nanotip-equipped ferroelectric templates produce 5.51 times larger Raman intensity, which can be further increased by >10.76 times by increasing the reaction time. The proposed SERS substrate owns the limit of detection <10−8 M and the enhancement factor of 2.3 × 109. The presented ferroelectric nanotips with permanent electrostatic field would open promising applications in the versatile areas, such as nanomaterial fabrication and optoelectronic devices.

Investigation on the correlation between solar absorption and the size of non-metallic nanoparticles

Solar heating with nanoparticles (NPs) exhibits great potential for photo thermal applications, such as direct absorption solar collector and photovoltaic photothermal system. The performance of NPs suspended in base fluid plays a major role in improving solar harvesting efficiency. Most researchers are focused on the optical properties of mental NPs due to their strong localized surface plasmon resonance (LSPR), resulting in a great solar absorption. To our best knowledge, theoretically and systematically studying on optical properties of non-metal NPs is still open. Therefore, we present a thorough investigation on the correlation between solar absorption and the size of CuO, carbon and graphite with the diameter range of 20–200 nm though using the finite-difference time-domain (FDTD) method. Results show that absorption and scattering cross sections of NPs have great sensitivity to particle size. The absorbed power increases with particle size growing. And solar absorption power for per unit volume of the three NPs has optimal diameter about 60 nm, 100 nm, 160 nm for carbon, graphite, and CuO, respectively. Graphite exhibits best average solar absorption efficiency, following by carbon and CuO except for particles smaller than about 30 nm. For particle diameter of 30 nm, carbon has better sunlight absorption property than that of graphite. This work aimed to provide guidelines for choosing non-metal particles and their optimal size for solar thermal utilization.

Tunable Three-Dimensional Plasmonic Arrays for Large Near-Infrared Fluorescence Enhancement.

Metal-enhanced fluorescence (MEF), resulting from the near-field interaction of fluorophores with metallic nanostructures, has emerged as a powerful tool for dramatically improving the performance of fluorescence-based biomedical applications. Allowing for lower autofluorescence and minimal photoinduced damage, the development of multifunctional and multiplexed MEF platforms in the near-infrared (NIR) windows is particularly desirable. Here, a low-cost fabrication method based on nanosphere lithography is applied to produce tunable three-dimensional (3D) gold (Au) nanohole-disc arrays (Au-NHDAs). The arrays consist of nanoscale glass pillars atop nanoholes in a Au thin film: the top surfaces of the pillars are Au-covered (effectively nanodiscs), and small Au nanoparticles (nanodots) are located on the sidewalls of the pillars. This 3D hole-disc (and possibly nanodot) construct is critical to the properties of the device. The versatility of our approach is illustrated through the production of uniform and highly reproducible Au-NHDAs with controlled structural properties and tunable optical features in the NIR windows. Au-NHDAs allow for a very large NIR fluorescence enhancement (more than 400 times), which is attributed to the 3D plasmonic structure of the arrays that allows strong surface plasmon polariton and localized surface plasmon resonance coupling through glass nanogaps. By considering arrays with the same resonance peak and the same nanodisc separation distance, we show that the enhancement factor varies with nanodisc diameter. Using computational electromagnetic modeling, the electric field enhancement at 790 nm was calculated to provide insights into excitation enhancement, which occurs due to an increase in the intensity of the electric field. Fluorescence lifetime measurements indicate that the total fluorescence enhancement may depend on controlling excitation enhancement and therefore the array morphology. Our findings provide important insights into the mechanism of MEF from 3D plasmonic arrays and establish a low-cost versatile approach that could pave the way for novel NIR-MEF bioapplications.

Copper Sulfide Nanodisks and Nanoprisms for Photoacoustic Ovarian Tumor Imaging.

Transvaginal ultrasound is widely used for ovarian cancer screening but has a high false positive rate. Photoacoustic imaging provides additional optical contrast to supplement ultrasound and might be able to improve the accuracy of screening. Here, we report two copper sulfide (CuS) nanoparticles types (nanodisks and triangular nanoprisms) as the photoacoustic contrast agents for imaging ovarian cancer. Both CuS nanoprisms and nanodisks were ~6 nm thick and ~26 nm wide and were coated with poly(ethylene glycol) to make them colloidally stable in phosphate buffered saline (PBS) for at least 2 weeks. The CuS nanodisks and nanoprisms revealed strong localized surface plasmon resonances with peak maxima at 1145 nm and 1098 nm, respectively. Both nanoparticles types had strong and stable photoacoustic intensity with detection limits below 120 pM. The circular CuS nanodisk remained in the circulation of nude mice (n=4) and xenograft 2008 ovarian tumors (n=4) 17.9-fold and 1.8-fold more than the triangular nanoprisms, respectively. Finally, the photoacoustic intensity of the tumors from the mice (n=3) treated with CuS nanodisks was 3.0-fold higher than the baseline. The tumors treated with nanodisks had a characteristic peak at 920 nm in the spectrum to potentially differentiate the tumor from adjacent tissues.

Excitation of Strong Localized Surface Plasmon Resonances in Highly Metallic Titanium Nitride Nano-Antennas for Stable Performance at Elevated Temperatures

New opportunities for plasmonic applications at high temperatures have stimulated interest in refractory plasmonic materials that show greater stability at elevated temperatures than the more commonly used silver and gold (Au). Titanium nitride (TiN) has been identified as a promising refractory material, with deposition of TiN thin films through techniques ranging from plasma-enhanced atomic laser deposition to sputter deposition to pulsed laser deposition, on a variety of substrates, including MgO, polymer, SiO2, and sapphire. A variety of plasmonic devices have been evaluated, including gratings, nanorods, and nanodisks. An implicit metric for TiN behavior has been the comparison of its plasmonic performance to that of Au, in particular at various elevated temperatures. This paper carries out a one-to-one comparison of bowtie nanoantennas formed of TiN and Au (on both Si and MgO substrates), examining the far-field characteristics, related to the measured near-field resonances. In both cases, the optic...

TUNABLE SURFACE PLASMON RESONANCES OF Au@TiO2 CORE-SHELL NANOPARTICLES ON THE DSSC (DYE SENSITIZED SOLAR CELLS) PERFORMANCE

Plasmonic core-shell nanoparticles, i.e. gold can improve the efficiency of Dye-sensitized Solar Cell by increase the light harvesting due to the strong near-field effect LSPR (Localized Surface Plasmon Resonance). To achieve maximum enhancement, the morphology of core-shell need to be optimized with coated either by insulator such as semiconductor, i.e. TiO2. In this paper, morphology of Au@TiO2 core-shell precisely control by various TiO2 volume and systematically study its influence on the plasmonic enhancement effect. A gold solution was prepared using Turkevich method. The crystal structure of the powders was determined by powder X-ray diffraction (XRD). The optical properties were measured by UV-Vis absorption spectroscopy using UV-Vis Lambda 750. The photocurrent action spectra or IPCE in visible light spectrum was obtained by adjusting wavelength of incident light, i.e. series connection of halogen lamp and monochromator. UV-Vis absorption spectra of core–shell showed the position of the surface plasmon Au band in the range of 500–550 nm. According to UV-Vis characterization, all samples studied show weak surface plasmon resonance response (~520 to 550 nm) as indicative of the thick TiO2 shells for individual core-shell Au@TiO2.Tunable Surface Plasmon Resonances of Au@TiO2 Core-shell Nanoparticles on the DSSC (Dye Sensitized Solar Cells) Performance