41 research outputs found
Large-Area Plasmonics on Self-Organized Wrinkled Nanopatterns
No full textThe focus of my PhD project consisted in the development of self-organized, large area, industrially scalable physical methods based on wrinkling instabilities to nanopattern and functionalize tunable plasmonic polymeric polydimetilsyloxane (PDMS) and solid-state glass surfaces, both transparent, non-toxic and cheap materials, for applications of significant technological interest in photonics and bio-sensing
Infrared Plasmonics via Self-Organized Anisotropic Wrinkling of Au/PDMS Nanoarrays
No full textPolydimethylsiloxane
(PDMS) templates are nanopatterned over large
areas to form uniaxial wrinkles by air plasma treatment on prestretched
samples. Ripple-like structures with tunable height/width aspect ratio
are so achieved. The anisotropic uniaxial PDMS modulations represent
an ideal platform for the confinement of plasmonic nanowire (NW) arrays
by grazing angle Au thermal deposition. This self-organized fabrication
method is suitable to be scaled to the industrial level as a single
step maskless process. The flexible NW arrays show monodisperse width
distribution and exhibit strongly dichroic optical properties. Localized
surface plasmon resonances (LSPR) of dipolar and multipolar character
are excited when light is linearly polarized orthogonally to the NW
major axis. The LSPR wavelength can be easily tuned across a remarkably
large spectral range from 600 to 1200 nm by engineering the NW width
and the PDMS ripple morphology. The PDMS/Au NW nanocomposite material
also shows relevant performance as a transparent flexible electrode
with sheet resistance on the order of 15 Ω/sq, a figure of merit
which is competitive with the best transparent conductive oxides
Large area nanostructuring of van der Waals materials for photon harvesting in the flat optics regime
No full textITO-free transparent plasmonic nano-electrodes via Ar Plasma irradiation for large area and flexible architectures
No full textFlat-optics hybrid MoS2/polymer films for photochemical conversion
No full textNovel light harvesting platforms and strategies are crucial to develop renewable photon to energy conversion technologies that overcome the current global energy and environmental challenges. Two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductor layers are particularly attractive for photoconversion applications but new ultra-compact photon harvesting schemes are urgently required to mitigate their poor photon absorption properties. Here, we propose a flat-optics scheme based on nanogrooved ultra-thin MoS2 layers conformally grown onto large area (cm2 scale) nanopatterned templates. The subwavelength re-shaping of the 2D-TMD layers promotes the excitation of photonic Rayleigh anomaly (RA) modes, uniquely boosting a strong in-plane electromagnetic confinement. By tailoring the illumination conditions, we demonstrate effective tuning of the photonic anomalies over a broadband visible spectrum across the absorption band of relevant polluting dye molecules. Thanks to the strong photonic in-plane confinement, we achieve a resonant enhancement of the photodissociation rate of methylene blue (MB) molecules, well above a factor of 2. These results highlight the potential of flat-optics photon harvesting schemes for boosting photoconversion efficiency in large-scale hybrid 2D-TMD/polymer layers, with a strong impact in various applications ranging from new-generation photonics to waste water remediation and renewable energy storage
Layer-by-Layer assembly of colloidal CsPbX3 Nanocrystals into solid-state films with controlled thickness
No full textWavelength-Dependent Plasmonic Photobleaching of Dye Molecules by Large-Area Au Nanostripe Arrays
No full textThe development of clean light-harvesting platforms and technologies is crucial in view of the urgent energy and environmental global challenges. Plasmonic nanoparticles show great promise in light-harvesting applications, but their fabrication is typically constrained to small-area laboratory-scale methods or to highly polluting wet chemistry approaches that are not suitable for environmental applications such as waste water recycling. In this work, we propose a self-organized method to fabricate largearea (cm(2), industrially scalable up to m(2)) plasmonic templates. Ordered Au nanostripe arrays supported on cheap, nontoxic sodalime glass substrates are prepared, showing a tunable plasmonic response. We demonstrate enhanced photochemical reactivity and photobleaching of highly polluting methylene blue molecules promoted by this self-organized plasmonic platform. We investigate this effect by tailoring the spectral overlap between the molecule absorption band and the plasmon resonance and by tuning the monochromatized excitation wavelength. This kind of study is completely lacking in the literature for big molecules with optical absorption bands in the visible range. We demonstrate the dominant role of plasmon-enhanced near-field optical effects over hot-carrier injection in amplifying photodissociation of colored dye molecules, thus paving the way to the engineering and optimization of light-harvesting platforms for waste water treatment, dye molecule sensing devices, and a broad range of other light-harvesting applications
Free-standing plasmonic nanoarrays for leaky optical waveguiding and sensing
Get PDFFlat optics nanogratings supported on thin free-standing membranes offer the opportunity to combine narrowband waveguided modes and Rayleigh anomalies for sensitive and tunable biosensing. At the surface of high-refractive index Si3N4 membranes we engineered lithographic nanogratings based on plasmonic nanostripes, demonstrating the excitation of sharp waveguided modes and lattice resonances. We achieved fine tuning of these optical modes over a broadband Visible and Near-Infrared spectrum, in full agreement with numerical calculations. This possibility allowed us to select sharp waveguided modes supporting strong near-field amplification, extending for hundreds of nanometres out of the grating and enabling versatile biosensing applications. We demonstrate the potential of this flat-optics platform by devising a proof-of-concept nanofluidic refractive index sensor exploiting the long-range waveguided mode operating at the sub-picoliter scale. This free-standing device configuration, that could be further engineered at the nanoscale, highlights the strong potential of flat-optics nanoarrays in optofluidics and nanofluidic biosensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen
Large-area flexible nanostripe electrodes featuring plasmon hybridization engineering
No full textMultifunctional flexible Au electrodes based on one-dimensional (1D) arrays of plasmonic gratings are nanofabricated over large areas with an engineered variant of laser interference lithography optimized for low-cost transparent templates. Au nanostripe (NS) arrays achieve sheet resistance in the order of 20 Ohm/square on large areas (∼ cm2) and are characterized by a strong and dichroic plasmonic response which can be easily tuned across the visible (VIS) to near-infrared (NIR) spectral range by tailoring their cross-sectional morphology. Stacking vertically a second nanostripe, separated by a nanometer scale dielectric gap, we form near-field coupled Au/SiO2/Au dimers which feature hybridization of their localized plasmon resonances, strong local field-enhancements and a redshift of the resonance towards the NIR range. The possibility to combine excellent transport properties and optical transparency on the same plasmonic metasurface template is appealing in applications where low-energy photon management is mandatory like e.g., in plasmon enhanced spectroscopies or in photon harvesting for ultrathin photovoltaic devices. The remarkable lateral order of the plasmonic NS gratings provides an additional degree of freedom for tailoring the optical response of the multifunctional electrodes via the excitation of surface lattice resonances, a Fano-like coupling between the broad localised plasmonic resonances and the collective sharp Rayleigh modes
