Quantitative study on the photoemission of AlGaN nanoarrays based on the three-dimensional transportation within a four-step process.

Photocathodes play a crucial role in photoelectronic imaging and vacuum electronic devices. The quantum efficiency of photocathodes, which determines their performance, can be enhanced through materials engineering. However, the quantum efficiency of conventional planar photocathodes remains consistently low, at around 25%. In this paper, we propose what we believe is a novel structure of AlGaN nanowire array to address this issue. We investigate the photoemission characteristics of the nanowire array using the "four-step" process, which takes into account optical absorption, electron transportation, electron emission, and electron collection. We compare the quantum efficiency of nanowire arrays with different structure sizes and Al components. After studying the effect of incident light at various angles on the nanowire array photocathode, we identify the optimal dimensional parameters: a height of 400∼500 nm and a wire width of 200∼300 nm. Furthermore, we improved the collection efficiency of the photocathode by introducing a built-in/external electric field, and obtained a 104.4% enhancement of the collection current with the built-in electric field, meanwhile the photocurrent was increased by 87% compared to the case without the external electric field. These findings demonstrate the potential of optimizing photocathode performance through the development of a novel model and adjustment of parameters, offering a promising approach for photocathode applications.

Porous Molybdenum Compound Design for Strong Microwave Absorption.

Exploring highly efficient microwave absorption (MA) materials with a facile preparation method is of great significance for tackling electromagnetic pollution and remains a challenge. Herein, ternary MoO2/Mo2C/Mo2N composites with porous structures are fabricated by a simple precursor pyrolysis process. The unique structure and multiple components, which could generate sufficient heterogeneous interfaces, are conducive to improve impedance matching, trigger polarization loss, and strengthen conduction loss. Profiting from the synergistic effect of multiple dissipation mechanisms, the composites exhibit exceedingly good MA performance. The minimum reflection loss value reaches -38.0 dB at 10.4 GHz when the thickness is 2.0 mm, and the maximum effective absorbing bandwidth is 4.11 GHz ranged from 12.41 to 16.52 GHz when the thickness is 1.5 mm. These strategies pave opportunities for rational design of Mo-related composites for high-efficiency electromagnetic-wave absorption performance.

Recent progress of gold nanostructures and their applications.

For noble metals, such as gold (Au) and silver (Ag), it is well-known that surface plasmons of their nanocrystals have significant spatial confinement and propagation loss due to the strong damping effect and the scattering between the plasmons and phonons. Noble metal nanostructures are usually referred to as "plasmonic nanostructures" in many studies. Based on the resonance effect of surface plasmons, the electromagnetic field can be localized on the subwavelength scale, which induces a booming new field of nanophotonics. Among the various nanostructures, Au nanostructures have received extensive attention both in fundamental research and technological fields due to their unique localized surface plasmon characteristics. These characteristics include strong optical extinction, near-field enhancement, and far-field scattering. By changing either the morphological parameters or the surrounding medium of nanostructures, the localized surface plasmon resonance (SPR) of Au nanostructures can be tuned in a large spectral region from visible to near infrared (Vis-NIR) wavelength. Corresponding to the experimental research, there are several numerical techniques that enable modeling the optical characteristics of Au nanostructures in different shapes and assemblies. The most popular technique is the finite-difference time-domain (FDTD) method for modeling various nanostructures and nanoscale optical devices. The accuracy of the computational models has been proven by reliable experimental data. In this review, we focused on Au nanostructures of different morphologies, such as nanorods, nanocubes, nanobipyramids and nanostars. Then combined with FDTD simulations, we described the effect of morphological parameters and the surrounding medium on the SPR properties of Au nanostructures. More and more achievements indicate that the surface plasmon effect is promising in many technical fields. In the last part, we summarize some typical applications of plasmonic Au nanostructures, such as high sensitivity sensors, photothermal conversion with hot electron effects and photoelectric devices, as well as plasmonic nanolasers.

Direct coating of gold nanolayers to enhance the oxidation resistance of copper nanowire flexible transparent conductive films.

Copper nanowire-based transparent conductive films have garnered extensive attention owing to their cost-effectiveness and comparable electrical properties. However, the inherent instability of copper nanowires (Cu NWs) has curtailed their extensive utility and applicability. Herein, we present durable Cu@Au NW/PET films exhibiting elevated photoelectric attributes and remarkable flexibility. After preparing Cu NWs, the purification operation allows the purity of the Cu NWs to reach about 98%. Subsequently, Cu@Au NWs/PET flexible transparent conductive films (FTCFs) were prepared through vacuum filtration of Cu NWs and direct treatment with chloroauric acid. The resulting Cu@Au NW-based FTCFs exhibit impressive attributes including a low sheet resistance of 30 ohms per square and a high optical transmittance of 90%, resulting in an exceptional figure of merit (FOM) of 99. Remarkably, the Cu@Au NWs/PET film showed remarkable flexibility, retaining its properties after 10 000 cycles of continuous bending. Stability assessments further affirm the sheet resistance of the Cu@Au NW FTCFs remains nearly unchanged over 75 days at ambient temperature. The strategic integration of a gold nanolayer, serving as a protective coating on the Cu NWs, yields substantial enhancements in both electrical conductivity and overall stability within the Cu NW FTCF architecture. Furthermore, the obtained Cu@Au NW films exhibit rapid heating capabilities, reaching a temperature of 67 °C within 30 seconds at 3.5 V and subsequently returning to room temperature at the same rate. In summary, the introduction of a Au protective layer can effectively enhance the oxidation resistance of Cu NWs, which has great application potential in FTCFs in the field of film heaters.

Exciton-polariton light-emitting diode based on a single ZnO superlattice microwire heterojunction with performance enhanced by Rh nanostructures.

One-dimensional (1D) wirelike superlattice micro/nanostructures have received considerable attention for potential applications due to their versatility and capability for modulating optical and electrical characteristics. In this study, 1D superlattice microwires (MWs), which are made of undoped ZnO and Ga-doped ZnO with periodic and alternating crystalline layers (ZnO/ZnO:Ga), were synthesized individually. Under optical excitation, a series of resonance peaks in the photoluminescence spectrum can be ascribed to polariton emission, which originates from the coupling interaction of the 1D photonic crystal and confined excitons along the wire direction. Using a p-type GaN layer as the hole transport layer, a kind of waveguide light source based on an individual ZnO/ZnO:Ga superlattice MW was proposed and constructed. By analysing the spatially resolved electroluminescence spectra, the observed multipeak was ascribed to exciton-polariton emission with a vacuum Rabi splitting of about 275 meV. Cladding with Rh nanostructures gives rise to appropriate ultraviolet plasmons, and the Rabi splitting energy of our device was enhanced up to 413 meV. The exciton-polariton properties were further examined using angle-resolved electroluminescence measurements. Therefore, individual superlattice MWs can act as optical microresonators to achieve photon-exciton coupling with a large Rabi splitting energy. The experimental results indicate that an individual ZnO/ZnO:Ga superlattice MW can be generally used in developing exciton-polariton luminescence/lasing light sources, particularly for constructing low-threshold/thresholdless lasers toward pragmatic applications.

Plasmonic and catalytic Au NBP@AgPd nanoframes for highly efficient photocatalytic reactions.

Heterogeneous metal nanostructures with excellent plasmonic performance and catalytic activity are urgently needed to realize efficient light-driven catalysis. Herein, we demonstrate the preparation of hollow Au nanobipyramid (NBP)@AgPd nanostructures by employing Au NBP@Ag nanorods as templates. The products could transform from Au NBP@AgPd nanoframes to nanocages, along with the redshift and broadening of the plasmon wavelength. Particularly, the plasmon intensity of these nanostructures remained considerable among the shape evolution process. Based on the selective absorption of CTAB, the Ag atoms on the side surfaces of the Au NBP@Ag nanorods were employed as the sacrificial templates to reduce Pd atoms through galvanic replacement. The reduced Pd and Ag atoms produced through the reduction reaction were preferably co-deposited on the corners and edges at the early stage and later deposited directly on the defect sites of the side facets, as more Ag atoms were released. The discontinued distribution of the Pd atoms gives an opportunity to etch away the Ag atoms in the cores, leading to the formation of hollow Au NBP@AgPd nanostructures after the etching process. It is worth noting that the deposition of the ultrathin AgPd nanoframe had little influence on the plasmonic properties of Au NBPs, as verified by electrodynamic simulations. The Au NBP@AgPd nanoframe showed great photocatalytic activity toward Suzuki coupling reactions under laser irradiation. Taken together, these results suggest that the hot electrons successfully transfer from Au NBP to the AgPd nanoframes to participate in the photocatalytic reactions. This study affords a promising route for the synthesis of anisotropic bimetallic nanostructures with excellent plasmonic performances.

Electrically driven whispering-gallery-mode microlasers in an n-MgO@ZnO:Ga microwire/p-GaN heterojunction.

In emerging miniaturized applications, semiconductor micro/nanostructures laser devices have drawn great public attentions of late years. The device performances of micro/nanostructured microlasers are highly restricted to the different reflective conditions at various side surfaces of microresonators and junction interface quality. In this study, an electrically driven whispering-gallery-mode (WGM) microlaser composed of a Ga-doped ZnO microwire covered by a MgO layer (MgO@ZnO:Ga MW) and a p-type GaN substrate is illustrated experimentally. Incorporating a MgO layer on the side surfaces of ZnO:Ga MWs can be used to reduce light leakage along the sharp edges and the ZnO:Ga/GaN interface. This buffer layer incorporation also enables engineering the energy band alignment of n-ZnO:Ga/p-GaN heterojunction and manipulating the current transport properties. The as-constructed n-MgO@ZnO:Ga MW/p-GaN heterojunction device can emit at an ultraviolet wavelength of 375.5 nm and a linewidth of about 25.5 nm, achieving the excitonic-related recombination in the ZnO:Ga MW. The broadband spectrum collapsed into a series of sharp peaks upon continuous-wave (CW) operation of electrical pumping, especially for operating current above 15.2 mA. The dominant emission line was centered at 378.5 nm, and the line width narrowed to approximately 0.95 nm. These sharp peaks emerged from the spontaneous emission spectrum and had an average spacing of approximately 5.5 nm, following the WGM cavity modes. The results highlight the significance of interfacial engineering for optimizing the performance of low-dimensional heterostructured devices and shed light on developing future miniaturized microlasers.

Dynamically regulated electroluminescence via strain engineering.

Dynamic regulation of the light-emission wavelength has important scientific significance for developing new electroluminescent devices and expanding the application scope to the fields of lighting, display, sensing, and human-machine interaction. In this work, an electroluminescent device with a dynamically tunable emission wavelength is achieved based on the piezoresistive effect. The tunable range can reach up to 12 nm as the external strain increases from 0% to 0.148%. Also, the luminescence mechanism of the device is systematically analyzed, and is shown to be mainly due to the transition of electrons in the ground state to the excitation state caused by thermal tunneling excitation with the participation of multi-phonons. The shift of the emission wavelength originates from the narrowing of the energy band structure under the tensile strain and the change of the crystal field around the defect centers. This work provides a new, to the best of our knowledge, strategy for the development of wavelength-tunable light-emitting devices.

Optimized plasmonic performances and derivate applications of Au nanobipyramids.

Gold nanobipyramids (AuBPs) with narrow size distribution and high monodispersity have driven intensive attention because they display more advantageous plasmonic properties than gold nanorods (AuNRs). Applications of AuBPs based on tunable plasmonic properties and enhanced electromagnetic fields are being widely investigated in recent years. In this article, we focused on the preparation of well-defined AuBPs using the seed-mediated method, the plasmonic properties, and the exploration of AuBP-supported derivatives. The synergetic contributions of penta-twinned and appropriate growth environment could produce high-purity AuBPs. Systematic comparisons of plasmonic properties between AuBPs and AuNRs are illustrated. In addition, the well-defined AuBPs can be used as a template to synthesize multi-metallic nanostructures. The development of the epitaxial growth based on the AuBPs and corresponding applications are introduced. This study will provide a guide for the fabrication of composite nanostructures and advance their plasmonic applications.

Comparative Study on Preparation Methods for Transparent Conductive Films Based on Silver Nanowires.

Silver nanowires, which have high optoelectronic properties, have the potential to supersede indium tin oxide in the field of electrocatalysis, stretchable electronic, and solar cells. Herein, four mainstream experimental methods, including Mayer-rod coating, spin coating, spray coating, and vacuum filtration methods, are employed to fabricate transparent conductive films based on the same silver nanowires to clarify the significance of preparation methods on the performance of the films. The surface morphology, conductive property, uniformity, and flexible stability of these four Ag NW-based films, are analyzed and compared to explore the advantages of these methods. The transparent conductive films produced by the vacuum filtration method have the most outstanding performance in terms of surface roughness and uniformity, benefitting from the stronger welding of NW-NW junctions after the press procedure. However, limited by the size of the membrane and the vacuum degree of the equipment, the small-size Ag films used in precious devices are appropriate to obtain through this method. Similarly, the spin coating method is suited to prepare Ag NWs films with small sizes, which shows excellent stability after the bending test. In comparison, much larger-size films could be obtained through Mayer-rod coating and spray coating methods. The pull-down speed and force among the Mayer-rod coating process, as well as the spray distance and traveling speed among the spray coating process, are essential to the uniformity of Ag NW films. After being treated with NaBH4 and polymethyl methacrylate (PMMA), the obtained Ag NW/PMMA films show great potential in the field of film defogging due to the Joule heating effect. Taken together, based on the advantages of each preparation method, the Ag NW-based films with desired size and performances are easier to prepare, meeting the requirements of different application fields.

Continuous-wave operation of an electrically pumped single microribbon based Fabry-Perot microlaser.

Fabry-Perot (FP) mode microlasers have been popularized and applied widely in on-chip coherent light sources because of the unique advantages of directional output emission. In this work, a heterojunction light-emitting diode (LED) made of a Ga-doped ZnO (ZnO:Ga) microribbon and p-GaAs template is fabricated. And its electroluminescence characteristics of strong coupling of exciton-photon and polariton lasing, in the blue-violet spectrum, were demonstrated under continuous-wave operation of an electrical injection. In the device structure, a single microribbon with a rectangular-shaped cross section can achieve the FP-mode lasing action by the optical oscillation between the two lateral sides of the microcrystals in the ultraviolet spectrum. As the reverse-current is below the threshold value, the device can have radiative polaritonic lighting directly from bilateral sides of the microribbon, yielding strong coupling between excitons and FP-mode microresonator. And the exciton-polariton coupling strengths characterized by a Rabi splitting energy were extracted to be 500 meV. Further, when the input current increased more than a certain value, strong laser illuminating developed as two sharp peaks at the lower energy shoulder of the spontaneous emission peak, and these oscillating modes can dominate the waveguide EL spectra. The experimental results can provide us with further unambiguous evidence that the lasing is originated from the polariton resonances for the microribbon with strong exciton-polariton coupling. Since single microribbon based optical FP-mode microresonators do not require additional feedback mirrors, their compact size and resulting low thresholds make them a powerful candidate to construct on-chip coherent light sources for future integrated nanophotonic and optoelectronic circuitry.

Plasmon-enabled spectrally narrow ultraviolet luminescence device using Pt nanoparticles covered one microwire-based heterojunction.

Owing to great luminescent monochromaticity, high stability, and independent of automatic color filter, low dimensional ultraviolet light-emitting diodes (LEDs) via the hyperpure narrow band have attracted considerable interest for fabricating miniatured display equipments, solid state lighting sources, and other ultraviolet photoelectrical devices. In this study, a near-ultraviolet LED composed of one Ga-doped ZnO microwire (ZnO:Ga MW) and p-GaN layer was fabricated. The diode can exhibit bright electroluminescence (EL) peaking at 400.0 nm, with a line width of approximately 35 nm. Interestingly, by introducing platinum nanoparticles (PtNPs), we achieved an ultraviolet plasmonic response; an improved EL, including significantly enhanced light output; an observed blueshift of main EL peaks of 377.0 nm; and a reduction of line width narrowing to 10 nm. Working as a powerful scalpel, the decoration of PtNPs can be employed to tailor the spectral line profiles of the ultraviolet EL performances. Also, a rational physical model was built up, which could help us study the carrier transportation, recombination of electrons and holes, and dynamic procedure of luminescence. This method offers a simple and feasible way, without complicated fabricating technology such as an added insulating layer or core shell structure, to realize hyperpure ultraviolet LED. Therefore, the proposed engineering of energy band alignment by introducing PtNPs can be employed to build up high performance, high spectral purity luminescent devices in the short wavelengths.

Flexible ultraviolet photodetector based on single ZnO microwire/polyaniline heterojunctions.

Flexible ultraviolet (UV) photodetectors are considered as potential building blocks for future-oriented photoelectric applications such as flexible optical communication, image sensors, wearable devices and so on. In this work, high-performance UV photodetector was fabricated via a facile combination of single ZnO microwire (MW) and p-type polyaniline. Due to the formation of effective organic/inorganic p-n junction, the as-prepared flexible UV photodetector based on ZnO MW/polyaniline hybrid heterojunction exhibits high performance (responsivity ∼ 60 mA/W and detectivity ∼ 2.0 ×1011 Jones) at the reverse bias of -1 V under the UV illumination. The ZnO MW/polyaniline photodetector displays short response/recovery times (∼ 0.44 s/∼ 0.42 s), which is less than that of most reported UV photodetectors based on ZnO/polymer heterojunction. The fast response speed and recovery speed can be attributed to the high crystallinity of ZnO MW, built-in electric field in space-charge region and the passivation of oxygen traps on the surface. Further, the photodetector using ZnO MW/polyaniline junctions shows excellent flexibility and stability under bent conditions. This work opens a new way to design next-generation high-performance, low-cost and flexible optoelectronic devices for lab-on-a-chip applications.

Plasmon-enhanced strong exciton-polariton coupling in single microwire-based heterojunction light-emitting diodes: erratum.

We provide a revised figure and the corrected related expressions of our previous publication [Opt. Express29(2), 1023(2021)10.1364/OE.414113].

Plasmon-enhanced strong exciton-polariton coupling in single microwire-based heterojunction light-emitting diodes.

Manipulating the strong light-matter coupling interaction in optical microresonators that are naturally formed by semiconductor micro- or nanostructures is crucial for fabricating high-performance exciton-polariton devices. Such devices can function as coherent light sources having considerably lower emission threshold. In this study, an exciton-polariton light-emitting diode (LED), made of a single ZnO microwire (MW) and a p-GaN substrate, serving as the hole injector, was fabricated, and its working characteristics, in the near-ultraviolet region, were demonstrated. To further improve the quality of the single ZnO MW-based optical microresonator, Ag nanowires (AgNWs) with ultraviolet plasmonic response were deposited on the MW. Apart from the improvement of the electrical and optical properties of the hexagonal ZnO MW, the optically pumped whispering-gallery-mode lasing characteristics were significantly enhanced. Furthermore, a single ZnO MW not covered, and covered by AgNWs, was used to construct a heterojunction LED. Compared with single bare ZnO MW-based LED, significant enhancement of the device performance was achieved, including a significant enhancement in the light output and a small emission band blueshift. Specifically, the exciton-polariton emission was observably enhanced, and the corresponding Rabi splitting energy (∼ 495 meV) was significantly higher than that of the bare ZnO MW-based LED (∼ 370 meV). That ultraviolet plasmons of AgNWs enhanced the exciton-polariton coupling strength was further confirmed via angle-resolved electroluminescence measurements of the single MW-based polaritonic devices, which clearly illustrated the presence of Rabi splitting and subband anti-crossing characteristics. The experimental results provide new avenues to achieve extremely high coupling strengths, which can accelerate the advancements in electrically driven high-efficiency polaritonic coherent emitters and nonlinear devices.

Self-powered ultraviolet photodetector based on an n-ZnO:Ga microwire/p-Si heterojunction with the performance enhanced by a pyro-phototronic effect.

In the present study, a heterojunction made of an individual ZnO microwire via Ga incorporation (ZnO:Ga MW) with a p-Si substrate was constructed to develop a self-powered ultraviolet photodetector. When operated under an illumination of 370 nm light with a power density of ∼ 0.5 mW/cm2, the device exhibited an excellent responsivity of 0.185 A/W, a large detectivity of 1.75×1012 Jones, and excellent stability and repeatability. The device also exhibited a high on/off photocurrent ratio up to 103, and a short rising and falling time of 499/412 µs. By integrating the pyro-phototronic effect, the maximum responsivity and detectivity increased significantly to 0.25 A/W and 2.30×1012 Jones, respectively. The response/recovery time was drastically reduced to 79/132 µs without an external power source. In addition, the effects of light wavelength, power density, and bias voltage on the photocurrent response mediated by the pyro-phototronic effect were systematically characterized and discussed. Our work not only provides an easy yet efficient procedure for constructing a self-powered ultraviolet photodetector but also broadens the application prospects for developing individual wire optoelectronic devices based on the photovoltaic-pyro-phototronic effect.

Photocurrent enhancement of AlxGa1-xN nanowire arrays photodetector based on coupling effects of pn junction and gradient component.

Ultraviolet photodetector has a variety of applications in medical diagnosis, civilian testing and military security. The enhancement of photo response has far been a hot topic regrading to the performance improvement of the devices. In this study, we proposed a self-powered photodetector based on AlxGa1-xN nanowire arrays (NWAs) utilizing axial pn junction integrating with gradient Al component. The merit of the coupling structure is demonstrated by theoretical model and simulations. The photoelectric conversion model is built based on a continuity equation derived by its corresponding boundary conditions. The photocurrent for a single nanowire and NWAs are respectively obtained. According to the simulation results of a single nanowire, the optimal nanowire height is obtained with a photocurrent enhancement up to 330%. For NWAs, the aspect ratio of NWAs and incident angle of light synergistically determine the output photocurrent. The optimal aspect ratio for NWAs is 1:1 with an optimal incident angle of 57°. This study provides a reliable method for the design of photodetectors with micro-nano structures.

Pt nanoparticles utilized as efficient ultraviolet plasmons for enhancing whispering gallery mode lasing of a ZnO microwire via Ga-incorporation.

Introducing nanostructured metals with ultraviolet plasmonic characters has attracted much attention for fabricating high performance optoelectronic devices in the shorter wavelength spectrum. In this work, platinum nanoparticles (PtNPs) with controlled plasmonic responses in ultraviolet wavelengths were successfully synthesized. To demonstrate the promising availability, PtNPs with desired sizes were deposited on a hexagonal ZnO microwire via Ga-doping (PtNPs@ZnO:Ga MW). Under ultraviolet illumination, typical near-band-edge emission of ZnO:Ga MW was considerably enhanced; meanwhile, the photocurrent is much larger than that of the bare MW. Thereby, the enhanced phenomena of a ZnO:Ga MW is related to localized surface plasmon resonances of the decorated PtNPs. A single MW with a hexagonal cross-section can be a potential platform to construct a whispering gallery mode (WGM) cavity due to its total inner wall reflection. Given this, the influence of PtNPs via ultraviolet plasmons on lasing features of the ZnO:Ga MW was tested. The lasing characteristics are significantly enhanced, including lasing output enhancement, a clear reduction of the threshold and the improvement of the quality factor. To exploit the working principle, PtNPs serving as powerful ultraviolet plasmons can couple with ZnO:Ga excitons, accelerating radiative recombination. Since fabricating stable, typical nanostructured metals with ultraviolet plasmons remains a challenging issue, the results illustrated in the work may offer a low-cost and efficient scheme for achieving plasmon-enhanced wide-bandgap semiconductor based ultraviolet optoelectronic devices with excellent performances.

High performance lasing in a single ZnO microwire using Rh nanocubes.

High-purity and size-controlled Rh nanocubes (RhNCs) with plasmonic responses in the ultraviolet spectrum range were synthesized; the ultraviolet plasmonic features of RhNCs have potential applications in wide bandgap semiconductors and optoelectronic devices because of their optical tunability and stability, as well as the compatibility with neighboring semiconductor micro/nanostructures. In this work, by incorporating RhNCs, the near-band-edge emission of a single ZnO microwire is considerably enhanced. When optically pumped by a fs pulsed laser at room temperature, RhNCs-plasmon enhanced high-performance whispering gallery mode (WGM) lasing characteristics, including lower lasing threshold, higher Q-factor, and lasing output enhancement, can be achieved from a single ZnO microwire covered by RhNCs. To further probe the modulation effect of RhNCs plasmons on the lasing characteristics of the ZnO microwires, time-resolved photoluminescence (TRPL) and electromagnetic simulation analyses were also performed. Based on our results, it can be concluded that size-controlled RhNCs with ultraviolet energy-tunable plasmons have the potential for use in optoelectronic devices requiring stable and high-performance in the short wavelength spectrum band owing to their unique ultraviolet plasmonic features.

Dielectric function modelling and sensitivity forecast for Au-Ag alloy nanostructures.

Plasmonic metal nanostructures are promising for chemical and biological sensor applications due to their high spectral sensitivity, defined as the relative shift in resonance wavelength with respect to the refractive index changes of the surroundings. In this work, the refractive index sensitivity (RI sensitivity) of one kind of core-shell nanostructure was studied, in which the gold nanobipyramid (AuBP) core was sheltered by the Au-Ag alloy shell. We investigated the dependence of the RI sensitivity and the figure of merit (FOM) of the localized surface plasmon resonance (LSPR) on the geometry and the composition of the nanostructures. Theoretical consideration on the LSPR revealed that the RI sensitivity of the nanostructures is determined by the bulk plasma wavelength, dielectric properties of the alloy and the geometrical parameters. To quantitatively explore the dependence of the RI sensitivity on the metal compositions and the aspect ratios of the nanostructures, the frequency-related dielectric properties of the alloy were calculated using the Drude-critical points model (DCPM). Then the calculated dielectric data were applied in the finite difference time domain (FDTD) solutions to simulate the optical spectra of the alloy nanostructures with various Ag concentrations. Experimentally, a series of fabrication processes were also carried out for the growth of a homogeneous Au-Ag alloy nanoshell on the surface of AuBPs using a wet-chemical method. The measured RI sensitivities agree well with the values predicted from FDTD simulations, indicating the availability, credibility and feasibility of the modelled dielectric data of the alloy. The DCPM and FDTD simulations can be combined to calculate the dielectric properties and forecast the sensitivity properties of the Au-Ag alloyed nanostructures with varying concentrations.