“Designing plasmonic nanoparticles for light trapping applications in solar cells”
Fiona J Beck
Optically driven localised surface plasmons can be excited on sub-wavelength metal particles, which can strongly scatter light and concentrate fields in sub-wavelength volumes. These particles have interesting optical properties: the nanoparticle shape and size, and the local dielectric environment determine the wavelength dependent scattering behaviour and the near field distribution. If these particles are fabricated on a high-index substrate, a large fraction of light is scattered into the optically dense medium. This can be exploited to couple incident sunlight into trapped modes in a solar cell, increasing the absorption in the active region. The challenge is then to design plasmonic structures that are strongly scattering, and that couple efficiently to underlying substrates.
In this talk, I will discuss the design of plasmonic nanoparticles for light trapping applications in solar cells. By investigating the interaction of light with nanoparticles on high index substrates we gain insight into the different types of scattering resonances that can be excited, which in turn allows us to intuitively understand the sensitivity of these modes to changes in the particle shape, and the details of the local dielectric environment. It also provides new design criteria for plasmonic structures for efficient light trapping, beyond the dipole model. These results indicate that it would be possible to design arrays of nanoparticles which would scatter strongly over the wavelengths at which light trapping is needed for a particular photovoltaic device. These types of arrays could be usefully employed to increase the absorption, and hence the efficiency of thin solar cells.
