Stefania D’Agostino

University of Pavia | UNIPV

Metal-halide semiconductor perovskites have received great attention for the development of stable and efficient light emitting diodes and lasers, since they combine high charge carrier mobility and light emission spectral-purity with low-cost fabrication methods. Nevertheless, the role of excitons, free carries and trap states in perovskite light...

By using time-dependent density functional theory, we investigate in a fully quantum mechanical framework the interactions, in an ultra-near-field regime, between a localized surface plasmon excitable in a silver tetrahedral cluster and a molecular exciton with excitation energy in the same range. We show that, for metal–molecule distances below 5...

State-of-the-art fabrication and characterization techniques are nowadays able to experimentally control light-matter interaction at sub-nanometer scales. Thus theoret- ical schemes able to overcome the limits of the classical vision and to fully take into account quantum mechanical effects are needed. In this work, we propose the Time-Dependent De...

We report theoretical evidence that bulk nonlinear materials weakly interacting with highly localized plasmonic modes in ultra-sub-wavelength metallic nanostructures can lead to nonlinear effects at the single plasmon level in the visible range. In particular, the two-plasmon interaction energy in such systems is numerically estimated to be compara...

In this paper, we report on the eect of metal oxidation on strong coupling interactions between silver nanostructures and a J-aggregated cyanine dye. We show that metal oxidation can sensibly aect the plexcitonic system, inducing a change in the coupling strength. In particular, we demonstrate that the presence of oxide prevents the appearance of R...

Quantization of plasmonic modes in ultra-sub-wavelength metallic nanostructures allows to strongly enhance the local electromagnetic field intensity. Thus, nonlinear effects can be amplified to a regime where the two-plasmon interaction energy is comparable with the plasmon linewidth (of the order of 100 meV) and the system becomes sensitive to sin...

We report a discrete dipole approximation approach to analyse the perturbations induced by silver nano-particles on the decay dynamics of a point-like emitter placed in their proximity. Due to the excitation of localized surface plasmons, metallic nano-particles behave like optical antennas and are able to convert localized fields into free- propag...

Exciton–polaritons in semiconductors are quasi-particles which have recently shown the capability to undergo phase transition into a coherent hybrid state of light and matter. The observation of such quasi-particles in organic microcavities has attracted increasing attention for their characteristic of reaching condensation at room temperature. In...

Imprinted, distributed feedback lasers are demonstrated on individual, active electrospun polymer nanofibers. In addition to advantages related to miniaturization, optical confinement and grating nanopatterning lead to a significant threshold reduction compared to conventional thin-film lasers. The possibility of imprinting arbitrary photonic cryst...

Laser architectures based on nanowires and nanofibers have attracted a continuously increasing interest in the last years. On page 6542, L. Persano, A. Camposeo, S. D'Agostino, D. Pisignano, and co‐workers demonstrate imprinted nanopatterned lasers that are realized on the surface of single, electrospun, light‐emitting polymer nanofibers. This meth...

In this work sharp silver nanotips are analyzed and proposed as useful plasmonic tools to reduce the threshold for the onset of strong coupling in the electromagnetic interaction of a point-like emitter with localized surface plasmons. If compared to similarly-sized spherical nanoparticles, conically-shaped nanoparticles turn out to be extremely us...

In the last few years, hybrid systems consisting of punctual sources and metallic nanostructures have been assembled and studied. Furthermore, the radiative coupling between the two counterparts has become a crucial aspect to be explored in nanophotonics and plasmonics. In this paper a numerical framework based on the Discrete Dipole Approximation...

In the realm of semiconductor nanomaterials, a crystal lattice heavily doped with cation/anion vacancies or ionized atomic impurities is considered to be a general prerequisite to accommodating excess free carriers that can support localized surface plasmon resonance (LSPR). Here, we demonstrate a surfactant-assisted nonaqueous route to anisotropic...

A full control of the interaction between confined plasmons and point sources of radiation is a central issue in molecular plasmonics. In this paper, a theoretical contribution towards a physical understanding on the localized surface plasmons excited into metallic nanocones by a point dipole is given. A numerical approach based on the discrete dip...

A theoretical control of the electromagnetic coupling between localized surface plasmons and pointlike sources of radiation is a relevant topic in nanoscience and nanophotonics. In this paper a numerical approach based on the discrete dipole approximation is presented as a practical and reliable computational tool to study the decay dynamics of a d...

Molecular plasmonics is a rapidly growing interdisciplinary science that aims at investigating the coupling, at the nanometer scale, between emitting molecules and metallic nanostructures. This metal–molecule electromagnetic interaction involves the excitation of localized and/or delocalized surface plasmons and is of great interest for a variety o...

In this paper authors present a numerical approach based on the Discrete Dipole Approximation, to compute the total, radiative and nonradiative decay rates of a point-like emitter coupled to an arbitrary-shaped metallic nanostructure. The method is initially applied to a 10 nm-diameter Ag nanosphere, where a perfect agreement between numerical and...

A theory of the interaction between a radiating dipole and the plasmonic excitations of a spherical metallic nanoshell in the quasistatic approximation is formulated. After a derivation of surface plasmon frequencies and a comparison with the corresponding modes of metal spheres and cavities, we introduce an expression for the effective volume for...

Roughness is an important feature in plasmonics. Nanoparticles with a nanoscale surface buckling or with protrusions out of surfaces display higher absorption efficiencies and surface-enhanced Raman scattering activities with respect to smooth surfaces. In this work the effects of the branches and of their electromagnetic coupling on the near-field...

A new approach to generate and manage white light from an organic light emitting diode is shown. It consists in the coupling of two microcavity resonators made of only metallic and organic layers, whose operation principle is analogous to that of two mechanical harmonic oscillators coupled by a spring (see figure). This approach allows the solution...

We investigate the ability of different density functional methods to describe the electronic properties of isolated gold clusters, self-assembled monolayers (SAM) of oligophenylthiols (including the depolarization effect), and the biphenylthiol/gold interface. To elucidate the role of the exchange interaction, we consider a hierarchy of functional...

In this paper a theoretical study of polarization properties of a silver nanosphere touching a homogeneous silver substrate and covered by oxide layers of increasing thickness, is reported. Oxide layers are often deposited on metallic nanostructures in metal-enhanced fluorescence (MEF) or surface-enhanced raman scattering experiments to avoid nonra...

The realization of white-light sources with a combination of high color rendering index (CRI), which is the average of the first eight rendering indices, and the deep-red color rendering R9 is an important challenge in the field of solid-state lighting. Herein, we report on a pure white hybrid light-emitting device combining a deep-blue emission fr...

Electromagnetic modelling is a fundamental tool to understand the localized surface plasmon resonances in metal nanoparticles and to provide a design strategy able to guide the development of complex plasmonic nanostructures. In this work we theoretically investigate the electromagnetic field enhancement of silver nanospheres on a substrate with an...

We investigate the role of the exact exchange in describing the biphenylthiol/gold interface. The study is performed by simulating the electronic properties of mercaptobiphenylthiol and aminobiphenylthiol molecules adsorbed on a Au(23) cluster, using local, semilocal and hybrid functionals and an effective exact exchange method, namely, the localiz...

We present an efficient ab initio atomic-orbital-based embedding scheme, which allows to describe depolarization effects in self-assembled organic monolayers (SAMs). The method includes periodic-boundary conditions, all multipole moments and local-field effects. Results for substituted oligophenyl SAM, in combination with conventional, hybrid and o...

We investigate the metal enhanced fluorescence by silver nanospheres on a thin silver substrate. Experimental measurements for core/shell colloidal nanocrystals embedded in a polymer matrix show a fluorescence enhancement factor of about 9. We apply the discrete dipole approximation method to describe the local-field enhancement factor (LFEF). We f...

Ab initio Density Functional Theory calculations are here reported to characterize the adsorption of methanethiol at the Cu (110) surface. Theoretical results suggest that the binding of the adsorbate to the substrate is rather weak and the molecular geometry is correspondingly almost unaffected by the adsorption. Otherwise, when CH3SH deprotonates...