Nanocubes-based patch antennas have been proven to be an interesting alternative to build nanocavities on larger areas and at lower cost than with classical clean room techniques. These nanocavities can support gap plasmons that make such devices suitable for light absorbing applications, both narrow or broadband depending on the size dispersion of the colloidal nanocubes that are used. Recently, a fabrication approach has been proposed that relies on an alkyldithiol self-assembled monolayer as a cavity spacer instead of the dielectric coating that is usually being used. Through this process it has been demonstrated both an enhanced reproducibility of the cavity resonance and a thinning of the cavity below the usual 3 nm limit. These caracteristics make such structures good candidates for nonlocality study because of the high electric field confinement that arises in very narrow gaps. This self assembled monolayer spacer is also an opportunity for incorporating electronic properties within the nanogap. In this perspective, the present work proposes both a synthesis and a two steps self-assembly of a clicked molecular rectifier monolayer to be embedded into nanopatch cavities. This way, this monolayer will act both as a mechanical spacer and a molecular diode, thus combining photonic and electronic properties.
The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the optogeometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on copper indium gallium selenide, perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles, and colored solar cells.
The photo conversion efficiencies of the 1st and 2nd generat ion photovoltaic solar cells are limited by the physical phenomena involved during the photo-conversion processes. An upper limit around 30% has been predicted for a monojunction silicon solar cell. In this work, we study 3rd generation solar cells named rectenna which could direct ly convert visible and infrared light into DC current. The rectenna technology is at odds with the actual photovoltaic technologies, since it is not based on the use of semi-conducting materials.
We study a rectenna architecture consist ing of plasmonic nano-antennas associated with rectifying self assembled molecular diodes. We first opt imized the geometry of plasmonic nano-antennas using an FDTD method. The optimal antennas are then realized using a nano-imprint process and associated with self assembled molecular diodes in 11- ferrocenyl-undecanethiol. Finally, The I(V) characterist ics in darkness of the rectennas has been carried out using an STM. The molecular diodes exhibit averaged rect ification ratios of 5.
The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the opto-geometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on CIGS, Perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles and colored solar cells.
We theoretically and experimentally study the structuration of organic solar cells in the shape of photonic crystal slabs.
Using a Finite Difference Time Domain (FDTD) method, we investigate the double structuration of the PEDOT:PSS
layer and the metallic electrode. By taking advantage of the optical properties of photonic crystals slabs, we show the
possibility to couple Bloch modes with very low group velocities in the active layer of the cells. Such Bloch modes, also
called slow Bloch modes (SBMs), allow increasing the lifetime of photons within the active layer. We show that an
absorption gain ranging between 4% and 11% is possible according to the band gap of the organic material. Finally, we
present experimental demonstration performed using nanoimprint to directly pattern the standard organic semiconductor
P3HT :PCBM blend in thin film form in the shape of a photonic crystal able to couple SBMs.
Experimental and numerical results concerning the influence of silver nanoparticles on the optical absorption of organic
devices are presented. The metallic nanoparticles (NPs) are placed inside an interpenetrated poly(3-hexylthiophene):
[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) layer using a physical vapor deposition technique. An
absorption enhancement by comparison to devices without NPs is shown. An increase of the absorption by annealing is
also observed. Moreover, calculations are performed via a numerical analysis based on a Finite Difference Time Domain
(FDTD) method. We demonstrate that the light absorption can mainly occur inside the active layer instead of inside the
Our work deals with the improvement of "light harvesting" in organic photovoltaic cells by using photonic nanostructures. We have theoretically studied a periodically nanostructured poly
(3-hexylthiophene)(P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) thin film in order to increase its absorption in the near infrared spectral range. We have used a software, based on the FDTD (Finite-Difference Time-Domain) method, to calculate the absorption of light in organics solar cells. We have also considered the nanostructured photoactive layer of solar cells as a photonic crystal
and we have computed band diagrams to study the dispersion curves of this structure. We have first studied a blend (bulk heterojunction) with the same proportions of P3HT and PCBM. This material
provide at this time the best results in terms of photovoltaic efficiency. Nevertheless, in order to improve the
transport of charges to the electrodes, a model with P3HT and PCBM independently nanostructured (ordered
heterostructure) was also used. Moreover, this periodic nanostructuration allows "slow Bloch modes" to be coupled
inside the device with a low group velocity of electromagnetic waves. Thus, the interaction duration between light and
organics materials is improved.
The P3HT/PCBM photonic crystal parameters have been adjusted to maximize the density of Bloch modes and to obtain
flat dispersion curves. We have found that the light matter interaction was strongly enhanced which resulted in a 35.6%
increase of absorption in the 600 nm to 700 nm spectral range. In order to realize nanostructured organic solar cells, we
are also developing an experimental prototype, based on a patented process, which allows to nanostructure several kinds of polymers.