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[IEEE 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Hyderabad (2017.12.18-2017.12.19)] 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Synthesis of Gold Nanorods with Tunable Surface Plasmon Resonance for Near-Infrared Biosensing Applications
摘要： Single-crystalline gold nanorods of average size 121nm x8.4nmwith defect free surface are synthesized with surface plasmon resonance in the near-infrared region. The surface plasmon resonance is readily tunable from 900-1300nm by maintaining the pH of the growth solution while varying the Au3+/Ag+ ratio.
关键词： surface plasmon resonance,sensing,gold nanorods
更新于2025-09-23 15:21:01
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Determination of the two-dimensional distributions of gold nanorods by multiwavelength analytical ultracentrifugation
摘要： Properties of nanoparticles are influenced by various parameters like size, shape or composition. Comprehensive high throughput characterization techniques are urgently needed to improve synthesis, scale up to production and make way for new applications of multi-dimensional particulate systems. In this study, we present a method for measuring two-dimensional size distributions of plasmonic nanorods in a single experiment. Analytical ultracentrifuge equipped with a multiwavelength extinction detector is used to record the optical and sedimentation properties of gold nanorods simultaneously. A combination of sedimentation and extinction properties, both depending on diameter and length of the dispersed nanorods, is used to measure two-dimensional distributions of gold nanorod samples. The length, diameter, aspect ratio, volume, surface and cross-sectional distributions can be readily obtained from these results. As the technique can be extended to other non-spherical plasmonic particles and can be used for determining relative amounts of particles of different shapes it provides complete and quantitative insights into particulate systems.
关键词： gold nanorods,nanoparticles,multiwavelength extinction detector,two-dimensional size distributions,analytical ultracentrifugation
更新于2025-09-23 15:21:01
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Effect of surface modification and laser repetition rate on growth, structural, electronic and optical properties of GaN nanorods on flexible Ti metal foil
摘要： The effect of flexible Ti metal foil surface modification and laser repetition rate in laser molecular beam epitaxy growth process on the evolution of GaN nanorods and their structural, electronic and optical properties has been investigated. The GaN nanostructures were grown on bare- and pre-nitridated Ti foil substrates at 700 °C for different laser repetition rates (10–30 Hz). It is found that the low repetition rate (10 Hz) promotes sparse growth of three-dimensional inverted-cone like GaN nanostructures on pre-nitridated Ti surface whereas the entire Ti foil substrate is nearly covered with film-like GaN consisting of large-sized grains for 30 Hz growth. In case of the GaN growth at 20 Hz, uniformly-aligned, dense (～8 × 109 cm?2) GaN nanorods are successfully grown on pre-nitridated Ti foil whereas sparse vertical GaN nanorods have been obtained on bare Ti foil under similar growth conditions for both 20 and 30 Hz. X-ray photoemission spectroscopy (XPS) has been utilized to elucidate the electronic structure of GaN nanorods grown under various experimental conditions on Ti foil. It confirms Ga–N bonding in the grown structures, and the calculated chemical composition turns out to be Ga rich for the GaN nanorods grown on pre-nitridated Ti foil. For bare Ti substrates, a preferred reaction between Ti and N is noticed as compared to Ga and N leading to sparse growth of GaN nanorods. Hence, the nitridation of Ti foil is a prerequisite to achieve the growth of dense and aligned GaN nanorod arrays. The X-ray diffraction, high resolution transmission electron microscopy and Raman studies revealed the c-axis growth of wurtzite GaN nanorods on Ti metal foil with good crystallinity and structural quality. The photoluminescence spectroscopy showed that the dense GaN nanorod possesses a near band edge emission at 3.42 eV with a full width at half maximum of 98 meV at room temperature. The density-controlled growth of GaN nanorods on a flexible substrate with high structural and optical quality holds promise for potential applications in futuristic flexible GaN based optoelectronics and sensor devices.
关键词： Ti metal foil,laser molecular beam epitaxy,optical properties,GaN nanorods,structural properties,surface modification,electronic properties,laser repetition rate
更新于2025-09-23 15:19:57
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High performance CsPbBr <sub/>3</sub> quantum dots photodetectors by using zinc oxide nanorods arrays as an electron-transport layer
摘要： The electron transport layer (ETL) in perovskite photodetectors is playing a vital role in highly efficient electron extraction. Herein, this work reports a perovskite photodetector based on hydrothermal-fabricated ZnO nanorods (NRs) as the ETL and hot-injection-fabricated CsPbBr3 quantum dot (QD) as the photoabsorber. The crystalline structure, morphologies, and photoluminescence (PL) of the materials and the physics mechanism of highly efficient electron extraction in the devices are characterized and analyzed. The PL and time-resolved PL confirm the reduced recombination and enhanced electron transport to the indium tin oxide anode. The photodetectors based on ZnO NRs/CsPbBr3 QDs exhibit enormous enhancement in the response parameters such as a rise time of 12 ms, a decay time of 38 ms, and an on/off ratio of 3000, compared with the photodetectors based on ZnO films/CsPbBr3 QDs. These results indicate that the fabricated ZnO NRs/CsPbBr3 QDs heterojunction has a wide prospect of future applications in photodetectors.
关键词： electron transport layer,photoluminescence,ZnO nanorods,perovskite photodetectors,CsPbBr3 quantum dots
更新于2025-09-23 15:19:57
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Tetragonal tungsten bronze phase thin films in the Ka??Naa??Nba??O system: Pulsed laser deposition, structural and dielectric characterizations
摘要： Pulsed laser deposition parameters have been determined to synthesize pure Tetragonal Tungsten Bronze (TTB) phase thin films in the (K,Na)-Nb-O system (KNN). In relation to the high volatility of alkaline elements, it was found that the target composition and the target-substrate distance are of first importance. The TTB phase was identified by X-ray and electron diffraction and the surface microstructure consisting mainly of nanorods supports the formation of hallmark of the TTB phase. Poly-oriented nanorods have been obtained on both C-plane sapphire and (111)Pt/TiO2/SiO2/(001)Si substrates whereas horizontal nanorods oriented along the (hk0) planes have been grown on (100) and (110) SrTiO3. All the nanorods are parallel together when grown on (110) SrTiO3 and they present two in-plane orientations rotated of 90° from each other on (100) SrTiO3. Dielectric characteristics (dielectric permittivity e r, and loss tangent tand ) have been measured at low (1 kHz - 1 MHz) and high (1 GHz - 40 GHz) frequencies, on films deposited on Pt coated silicon and sapphire, respectively. A value of e r = 200 at 1 kHz with tand = 0.015 were measured in a parallel plate capacitor configuration, whereas e r = 130 and tand = 0.20 at 10 GHz were retrieved from transmission lines printed on the KNN TTB thin film grown on C-plane sapphire. Raman investigations of the TTB films were performed in the temperature range 77 - 873 K, confirming the TTB phase formation and the absence of structural transition. Piezoelectric Force Microscopy measurements evidenced a piezoelectric signal although no switching could be performed. However the dielectric measurements, complicated by high leakage currents when a DC voltage was applied, did not evidence any proof of ferroelectricity for the undoped KNN TTB films whereas results reported on other niobates (A,A')0.6Nb10O30 (with A: K, Na and A': Sr, Ba, Ca) have shown Curie temperatures, lying between 156°C and 560°C, separating the paraelectric phase (space group: P4/mbm N°127) and the ferroelectric one (space group: P4bm N°100).
关键词： Tetragonal Tungsten Bronze,Nanorods,Dielectric characterizations,K-Na-Nb-O system,Pulsed laser deposition
更新于2025-09-23 15:19:57
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Fast-Response and Self-Powered Cu <sub/>2</sub> O/ZnO Nanorods Heterojunction UV-Visible (570 nm) Photodetectors
摘要： A fast, self-powered photodetector (PD) capable of UV to visible (570 nm) sensing based on the p-Cu2O/n-ZnO nanorods (NRs) heterostructure is reported. The PD shows a spectral response range from 380 nm to 570 nm, which is suitable for ambient light sensing applications. The PD exhibits good rectifying characteristics with a low leakage current and a low turn-on voltage of ～0.3 V. The responsivities of the self-powered PD are 0.24 A W?1 and 0.06 A W?1 at 380 and 450 nm, respectively. The rise/recovery time of the PD are 0.02/0.03 s and 0.01/0.02 s for UV (370 nm) and visible light (450 nm), respectively. Upon UV light illumination, the long, persistent photocurrent (or recovery time) caused by ZnO NRs can be eliminated using the self-powered mode.
关键词： fast-response,p-Cu2O/n-ZnO nanorods heterostructure,self-powered photodetector,UV-Visible sensing
更新于2025-09-23 15:19:57
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Thermoplasmonica??Activated Hydrogel Based Dynamic Light Attenuator
摘要： This work describes the morphological, optical, and thermo-optical properties of a temperature-sensitive hydrogel poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) [P(NIPAm-co-NIPMAm]) film containing a specific amount of gold nanorods (GNRs). The light-induced thermoplasmonic heating of GNRs is used to control the optical scattering of an initially transparent hydrogel film. A hydrated P(NIPAm-co-NIPMAm) film is optically clear at room temperature. When heated to temperatures over 37 °C via light irradiation with a resonant source (λ = 810 nm) to the GNRs, a reversible phase transition from a swollen hydrated state to a shrunken dehydrated state occurs. This phenomenon causes a drastic and reversible change in the optical transparency from a clear to an opaque state. A significant red shift (≈30 nm) of the longitudinal band can also be seen due to an increased average refractive index surrounding the GNRs. This change is in agreement with an ad hoc theoretical model which uses a modified Gans theory for ellipsoidal nanoparticles. Morphological analysis of the composite film shows the presence of well-isolated and randomly dispersed GNRs. Thermo-optical experiments demonstrate an all-optically controlled light attenuator (65% contrast ratio) which can be easily integrated in several modern optical applications such as smart windows and light-responsive optical attenuators.
关键词： gold nanorods,active plasmonics,optical attenuators,polymers,optical transparency,hydrogels,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates
摘要： We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency.
关键词： chemical bath deposition,nanoscale heterojunctions,ZnO nanorods,nanoprobe in the scanning electron microscope,current-voltage characteristics,annealing,focused ion beam patterning
更新于2025-09-23 15:19:57
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Plasmonic Fano Resonance in Homotactic Aluminum Nanorod Trimer: the Key Role of Coupling Gap
摘要： Recently, the Fano effect of aluminum nanostructures has attracted a lot of attentions in several detector and sensor applications, but the role of coupling gap in it remains unintuitive. In this paper, a homotactic aluminum rod trimer (HART) is designed to form the plasmonic Fano resonances and visualize the important role of coupling gap size. The plasmon hybridization model and far field images were used to qualitatively describe the formation mechanism of Fano resonance. The simulation results intuitively show that the Fano dip of HART with a smaller coupling gap size has a higher red-shift speed when increasing the refractive index of surrounding environment or the length of HART with a fixed axial ratio (LS/LL = 0.6). Our study provides the insights to the key role of coupling gap in the performance of Fano structures.
关键词： Fano resonance,Aluminum nanorods,Far field,Plasmon,Coupling gap
更新于2025-09-23 15:19:57
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Hybrid of Graphene based on quaternary Cu2ZnNiSe4 a??WO3 Nanorods for Counter Electrode in Dye-sensitized Solar Cell Application
摘要： A novel nanohybrid of graphene-based Cu2ZnniSe4 with WO3 nanorods (G-CZNS@W) was successfully synthesized via a simple hydrothermal method to use as a counter electrode (ce) for dye-sensitized solar cells (DSSCs). The characterization technique confirmed the structural and morphologies of the G-CZNS@W nanohybrid, which could show rapid electrons transfer pathway through the WO3 nanorods. Moreover, the as-fabricated G-CZNS@W nanohybrid exhibited synergetic effect between G-cZnS and a Wo3 nanorod, which could affect the electrocatalytic activity towards triiodide reaction. The nanohybrid exhibits an excellent photovoltaic performance of 12.16%, which is higher than that of the standard pt electrode under the same conditions. the G-cZnS@W nanohybrid material as ce thus offers a promising low-cost Pt-free counter electrode for DSSC.
关键词： Counter Electrode,Graphene,WO3 nanorods,Dye-sensitized Solar Cells,Cu2ZnniSe4
更新于2025-09-23 15:19:57