Exploiting the localized surface plasmon modes in gold triangular nanoparticles for sensing applications

In this study we investigate and exploit, for optical sensing, the surface plasmon excitation in gold triangular nanoparticles with high aspect ratios (i.e., the ratio of the edge length of the triangles with the height) prepared by nanosphere lithography. As shown previously, the shape and size of these nanoparticles were used to tune their optical properties, monitored by far field extinction spectroscopy. Interestingly, several localized surface plasmon resonances were detected in the visible and near infrared regions and were attributed to dipole and quadrupole modes. These modes, identified from numerical simulations, "red-shift'' as the aspect ratio of the particles increases. The plasmon modes observed for larger triangles exhibit unexpected sensitivity with a change in the refractive index. From experiments and numerical simulations, this higher sensitivity has been attributed to an increase of the local field enhancement for sharper tips. This new effect can provide important information for the design of particles as building blocks for sensing applications

Plasmonic absorption enhancement in organic photovoltaics

Organic solar cells have a strong potential for the near future, because their material and fabrication costs can be much smaller than for traditional technologies. However, in order to become commercially viable their efficiency needs to increase. One of the novel, interesting techniques to increase the light absorption is by including plasmonic enhancements. These metallic features instigate strong, local resonances which trap the light in the very thin layers. In this work we report rigorous numerical investigations of organic cells with embedded metallic nanoparticles and with patterned metallic electrodes. The state-of-the-art material P3HT:PCBM is employed as the active layer. We show that in both cases, with particles or with patterned electrodes, a strong enhancement is achievable, with roughly an increase of up to 50% in the solar light absorption. Such enhancements could prove crucial for more efficient energy devices

Angle insensitive enhancement of organic solar cells using metallic gratings

A

Tailored and tapered metallic gratings for enhanced absorption or transmission

Plasmonic structures, such as metallic gratings and apertures, provide unusual abilities to modify the absorption or the transmission of thin-layered devices. In order to optimize the absorption in thin-film solar cells, we introduce complex grating geometries, implementing multiple periodicities and blazing. These gratings optimize the diffraction efficiency and increase the number of accessible modes. On the other hand, in order to achieve enhanced transmission at infrared wavelengths, we propose tapered apertures. The non-resonant funnelling phenomena provide for broadband and wide-angle focusing opportunities