Embedded Ag@SiO<inf>2</inf> nanoparticles for enhanced solar absorption in thin film photovoltaics

Abstract

We analytically determine the contribution of plasmonic nanospheres embedded in absorbing media to total optical absorption. We estimate gains of ~30% for a 1 μm μc-Si solar cell using 54 nm silica-coated silver nanoparticles.

Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media

“…The initial conditions of the angular functions for the first few orders are shown in Eqs. (20) and (21). Subsequent terms can be determined using upward recursion relationships for an increasing order n:…”

“…Interestingly, a strong peak is found for small, primarily absorbing gold particles in the near-infrared in silicon, showing that the substantial field line disruption for a strongly interacting plasmonic resonance can yield significant absorption enhancement in the near-field medium, as well as the particle. A full accounting of the net effect of the particles on absorption in a thin film would also need to include the angular dependent optical path length increase effect of scattering from the plasmonic particle within the absorbing media, and boundary effects such as internal scattering at interfaces and electron trapping at the surface of metal particles, as we have considered in our recent work [20]. The results here can guide us in determining the use of plasmonic particles for substantially improving the near-field absorption in a medium and the actual location of near-field enhancement necessary to define the useful maximum density of particles embedded in a medium to achieve optimal enhancement.…”

“…One important application of a point-by-point approach is in estimating the plasmonic enhancement of thin film solar photovoltaics or optical sensors [20]. In this case, the charge collection efficiency can be limited by the thickness, creating a tradeoff with the corresponding optical absorption.…”