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Nanostructures for Light Trapping in Thin Film Solar Cells
摘要： Thin ?lm solar cells are one of the important candidates utilized to reduce the cost of photovoltaic production by minimizing the usage of active materials. However, low light absorption due to low absorption coe?cient and/or insu?cient active layer thickness can limit the performance of thin ?lm solar cells. Increasing the absorption of light that can be converted into electrical current in thin ?lm solar cells is crucial for enhancing the overall e?ciency and in reducing the cost. Therefore, light trapping strategies play a signi?cant role in achieving this goal. The main objectives of light trapping techniques are to decrease incident light re?ection, increase the light absorption, and modify the optical response of the device for use in di?erent applications. Nanostructures utilize key sets of approaches to achieve these objectives, including gradual refractive index matching, and coupling incident light into guided modes and localized plasmon resonances, as well as surface plasmon polariton modes. In this review, we discuss some of the recent developments in the design and implementation of nanostructures for light trapping in solar cells. These include the development of solar cells containing photonic and plasmonic nanostructures. The distinct bene?ts and challenges of these schemes are also explained and discussed.
关键词： solar cells,plasmonic nanostructures,light trapping,thin ?lms,photonic nanostructures
更新于2025-09-16 10:30:52
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Ultrasensitive SERS-Based Plasmonic Sensor with Analyte Enrichment System Produced by Direct Laser Writing
摘要： We report an easy-to-implement device for surface-enhanced Raman scattering (SERS)-based detection of various analytes dissolved in water droplets at trace concentrations. The device combines an analyte-enrichment system and SERS-active sensor site, both produced via inexpensive and high-performance direct femtosecond (fs)-laser printing. Fabricated on a surface of water-repellent polytetrafluoroethylene substrate as an arrangement of micropillars, the analyte-enrichment system supports evaporating water droplet in the Cassie–Baxter superhydrophobic state, thus ensuring delivery of the dissolved analyte molecules towards the hydrophilic SERS-active site. The efficient pre-concentration of the analyte onto the sensor site based on densely arranged spiky plasmonic nanotextures results in its subsequent label-free identification by means of SERS spectroscopy. Using the proposed device, we demonstrate reliable SERS-based fingerprinting of various analytes, including common organic dyes and medical drugs at ppb concentrations. The proposed device is believed to find applications in various areas, including label-free environmental monitoring, medical diagnostics, and forensics.
关键词： SERS,direct laser processing,femtosecond laser pulses,medical drugs,superhydrophobic textures,plasmonic nanostructures,analyte enrichment
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Towards Near-Field Coupling of Surface Plasmon Polaritons across Few-Nanometer Gaps between two Laterally Tapered Gold Waveguides
摘要： Nanofocusing of light in combination with an efficient energy transfer of metallic nanostructures is a key task towards ultrafast, all-optical switching on the nanoscale. A possible realization of such a device is based on two tapered plasmonic nanostructures separated by a few-nanometer gap, in which information transport is controlled via strong coupling of the electromagnetic near-field and excitonic molecules in the gap region of the waveguides. The fabrication of such mesoscopic nanostructures that can concentrate free-propagating light to few-nanometers dimensions remains challenging due to the desired nanometer precision in the gap region. Here, we report on the fabrication of a plasmonic nanostructures consisting of a pair of both striped and tapered waveguides in 200 nm thick Au films with gap sizes and radii of curvature down to 11 nm using a Focused Ion Beam-based “Sketch and Peel” lithography process. Curved focused-ion beam written gratings in the waveguides enable the in- and out-coupling and focusing of surface plasmon polaritons into the nanostructure. The propagation of these SPPs is afterwards monitored using far-field confocal microscopy. We find a relatively constant transmission of light for large gap sizes, accompanied by a drastically increase for gap sizes below 20 nm. This increase for small gap sizes can be approximated best by fitting an exponential decay with a decay length of 8 nm suggesting a significant energy transport through near-field coupling of the two waveguides. These experimental findings are in accordance to finite element method and finite difference time domain calculations that show a strong localization of the electric field in the gap region of the two waveguides. The profound electric field strength and the spatial confinement of the electric fields suggest such plasmonic waveguides as prototypical structures for probing the strong coupling between propagating surface plasmon polaritons in adjacent, however separated plasmonic waveguides on one hand and between SPP waves and single quantum emitters that are placed in the gap region of the waveguides on the other hand. The realization of such coupling could enable the ultrafast, remote switching on the nanoscale.
关键词： ultrafast switching,nanofocusing,near-field coupling,surface plasmon polaritons,plasmonic nanostructures
更新于2025-09-16 10:30:52
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Probing Specificity of Protein–Protein Interactions with Chiral Plasmonic Nanostructures
摘要： Protein?protein interactions (PPIs) play a pivotal role in many biological processes. Discriminating functionally important well-defined protein?protein complexes formed by specific interactions from random aggregates produced by nonspecific interactions is therefore a critical capability. While there are many techniques which enable rapid screening of binding affinities in PPIs, there is no generic spectroscopic phenomenon which provides rapid characterization of the structure of protein?protein complexes. In this study we show that chiral plasmonic fields probe the structural order and hence the level of PPI specificity in a model antibody?antigen system. Using surface-immobilized Fab′ fragments of polyclonal rabbit IgG antibodies with high specificity for bovine serum albumin (BSA), we show that chiral plasmonic fields can discriminate between a structurally anisotropic ensemble of BSA-Fab′ complexes and random ovalbumin (OVA)-Fab′ aggregates, demonstrating their potential as the basis of a useful proteomic technology for the initial rapid high-throughput screening of PPIs.
关键词： specificity,Protein?protein interactions,structural order,chiral plasmonic nanostructures,high-throughput screening
更新于2025-09-16 10:30:52
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Enhancing Quantum Yield in Strained MoS2 Bilayers by Morphology-controlled Plasmonic Nanostructures towards Superior Photodetectors
摘要： Recently, extracting hot electrons from plasmonic nanostructures and utilizing them to enhance the optical quantum yield of 2D transition-metal dichalcogenides (TMDs) have been topics of interest in the field of optoelectronic device applications, such as solar cells, light emitting diodes, photodetectors and so on. The coupling of plasmonic nanostructures with nanolayers of TMDs depends on the optical properties of the plasmonic materials, including radiation pattern, resonance strength, and hot electron injection efficiency. Herein, we demonstrate the augmented photodetection of a large-scale, transfer-free bilayer MoS2, by decorating this TMD with four different morphology-controlled plasmonic nanoparticles. This approach allows engineering the bandgap of the bilayer MoS2 due to localized strain that stems up from plasmonic nanoparticles. In particular, the plasmonic strain blue shifts the band gap of bilayer MoS2 with 32 times enhanced photoresponse demonstrating immense hot electron injection. Besides, we observed the varied photoresponse of MoS2 bilayer hybridized with different morphology controlled plasmonic nanostructures. Although, hot electron injection was a substantial factor for photocurrent enhancement in hybrid plasmonic-semiconductor devices, our investigations further show that other key factors such as highly directional plasmonic modes, high aspect-ratio plasmonic nanostructures and plasmonic strain induced beneficial band-structure modifications were crucial parameters for effective coupling of plasmons with excitons. As a result, our study sheds light on designing highly tailorable plasmonic nanoparticles integrated transition metal dichalcogenide-based optoelectronic devices.
关键词： Plasmonic Nanostructures,Strained MoS2 Bilayers,Quantum Yield,Photodetectors
更新于2025-09-16 10:30:52
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Strongly coupled, high-quality plasmonic dimer antennas fabricated using a sketch-and-peel technique
摘要： A combination of helium- and gallium-ion beam milling together with a fast and reliable sketch-and-peel technique is used to fabricate gold nanorod dimer antennas with an excellent quality factor and with gap distances of less than 6 nm. The high fabrication quality of the sketch-and-peel technique compared to a conventional ion beam milling technique is proven by polarisation-resolved linear dark-field spectromicroscopy of isolated dimer antennas. We demonstrate a strong coupling of the two antenna arms for both fabrication techniques, with a quality factor of more than 14, close to the theoretical limit, for the sketch-and-peel–produced antennas compared to only 6 for the conventional fabrication process. The obtained results on the strong coupling of the plasmonic dimer antennas are supported by finite-difference time-domain simulations of the light-dimer antenna interaction. The presented fabrication technique enables the rapid fabrication of large-scale plasmonic or dielectric nanostructures arrays and metasurfaces with single-digit nanometer scale milling accuracy.
关键词： helium-ion beam lithography,near-field enhancement,strong coupling,plasmonic nanostructures,sketch and peel,quality factor,single-particle dark-field spectroscopy
更新于2025-09-16 10:30:52
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Ultrafast Plasmonic Optical Switching Structures and Devices
摘要： Plasmonic structures possess rich physics related to the sensitivity of plasmon resonance to the change in the environmental dielectric constant, the enhanced light scattering and optical extinction, and the local field enhancement enabled strong light-matter interactions, which have been applied in refractive-index sensors, optical feedback in various micro- or nano-cavity lasers, surface enhanced Raman scattering spectroscopy, and high-sensitivity molecular detection. However, ultrafast optical response is another important aspect of plasmons, which can be utilized to achieve switching of optical signals in different spectral bands. These optical switching designs are very important for applications in optical logic circuits and optical communication system. In this review, we summarize a series of reports on ultrafast plasmonic optical switches, where we focus our discussions on the structural and device designs, instead of on their physics. By categorizing the designs of optical switches into different groups by their featured performances, we intend to propose the development trend and the commonly interested mechanisms of such ultrafast optical switches. We hope this review will supply helpful concepts and technical approaches for further development and new applications of ultrafast optical switching devices.
关键词： plasmonic device,metal oxides,plasmonic nanostructures,ultrafast optical switching,noble metals,surface plasmon polariton,hybrid plasmons,2D materials
更新于2025-09-12 10:27:22
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Plasmonic Nanolenses Produced by Cylindrical Vector Beam Printing for Sensing Applications
摘要： Interaction of complex-shaped light fields with specially designed plasmonic nanostructures gives rise to various intriguing optical phenomena like nanofocusing of surface waves, enhanced nonlinear optical response and appearance of specific low-loss modes, which can not be excited with ordinary Gaussian-shaped beams. Related complex-shaped nanostructures are commonly fabricated using rather expensive and time-consuming electron- and ion-beam lithography techniques limiting real-life applicability of such an approach. In this respect, plasmonic nanostructures designed to benefit from their excitation with complex-shaped light fields, as well as high-performing techniques allowing inexpensive and flexible fabrication of such structures, are of great demand for various applications. Here, we demonstrate a simple direct maskless laser-based approach for fabrication of back-reflector-coupled plasmonic nanorings arrays. The approach is based on delicate ablation of an upper metal film of a metal-insulator-metal (MIM) sandwich with donut-shaped laser pulses followed by argon ion-beam polishing. After being excited with a radially polarized beam, the MIM configuration of the nanorings permitted to realize efficient nanofocusing of constructively interfering plasmonic waves excited in the gap area between the nanoring and back-reflector mirror. For optimized MIM geometry excited by radially polarized CVB, substantial enhancement of the electromagnetic near-fields at the center of the ring within a single focal spot with the size of 0.37λ2 can be achieved, which is confirmed by Finite Difference Time Domain calculations, as well as by detection of 100-fold enhanced photoluminescent signal from adsorbed organic dye molecules. Simple large-scale and cost-efficient fabrication procedure offering also a freedom in the choice of materials to design MIM structures, along with remarkable optical and plasmonic characteristics of the produced structures make them promising for realization of various nanophotonic and biosensing platforms that utilize cylindrical vector beam as a pump source.
关键词： plasmonic nanostructures,cylindrical Vector Beam printing,Sensing Applications,nanofocusing,plasmonic nanolenses
更新于2025-09-12 10:27:22
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Plasmonic Metamaterials for Nanochemistry and Sensing
摘要： Plasmonic nanostructures were initially developed for sensing and nanophotonic applications but, recently, have shown great promise in chemistry, optoelectronics, and nonlinear optics. While smooth plasmonic films, supporting surface plasmon polaritons, and individual nanostructures, featuring localized surface plasmons, are easy to fabricate and use, the assemblies of nanostructures in optical antennas and metamaterials provide many additional advantages related to the engineering of the mode structure (and thus, optical resonances in the given spectral range), field enhancement, and local density of optical states required to control electronic and photonic interactions. Focusing on two of the many applications of plasmonic metamaterials, in this Account, we review our work on the sensing and nanochemistry applications of metamaterials based on the assemblies of plasmonic nanorods under optical, as well as electronic interrogation.
关键词： field enhancement,sensing,localized surface plasmons,optical antennas,nanochemistry,optical resonances,electronic interrogation,surface plasmon polaritons,metamaterials,Plasmonic nanostructures
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Coherent Control of the Non-Instantaneous Response of Plasmonic Nanostructes
摘要： Nonlinear metamaterials have revolutionized nonlinear optics, allowing novel abilities that expand the current available nonlinear material capabilities. Due to their unique response, nanoparticles (NP's) have been the subject of research in numerous fields ranging from physics, engineering, biology, medicine and others. Understanding their physical mechanism and properties has enabled unprecedented capabilities in linear and nonlinear optics, sensing, theragnostic biomedical optics, material classifications of molecular structures as complicated as DNA or sensitive as oxygen singlets and much more [1-4]. A complete theoretical description, based on the nonlinear scattering theory, has been found suitable to describe the geometrical contribution of nanostructures (NSs) to their nonlinear response [5]. Yet, until now, a comprehensive theory has been investigated only for the instantaneous nonlinear response. A full response, including the resonant non-instantaneous behavior brought about by their resonant linewidth, has not yet been studied. We experientially demonstrate variance in the nonlinear response by coherently controlling the electric field. We show, for the first time to our knowledge, resonant non-instantaneous properties by coherent control measurements of nonlinear second harmonic generation (SHG) in resonant media. (see Figure 1). In contrary to common perception, we find that transform limited pulses do not yield the strongest nonlinearity in SHG. Approaching strong fields, a decrease in nonlinear behavior is not captures in traditional nonlinear models. We develop a theoretical framework, analogous to a resonant 3 level interaction, capturing non-instantaneous resonant phenomena portraying resonant effects beyond the weak field two-photon description. These include deviations from the conventional SHG nonlinearity which commonly is proportional to the square of the fundamental field intensity (see Figure 2.a). We also show that with changing the localized surface plasmonic resonant wavelength relative to the source's central wavelength, a shift in energy distribution and intensity emerges in the SH process pointing to the relative position of the resonant frequency (see Figure 2.b).
关键词： Nonlinear metamaterials,nanoparticles,second harmonic generation,nonlinear optics,plasmonic nanostructures
更新于2025-09-12 10:27:22