Silicon solar cell enhancement by plasmonic silver nanocubes

Abstract

Our paper presents a detailed numerical simulation and experimental study of the efficiency enhancement gained by optimizing metal nanocubes incorporated on the surface of silicon solar cells. We investigate the effects of nanoparticle size, surface coverage and spacer layer thickness on solar absorption and cell efficiency. The fabrication of nanocubes on solar cells is also presented, with the trends observed in simulation verified through experimental data. Testing reveals that nanocubes show worse performance than nanospheres when sitting directly on the silicon substrate; however, enhancement exceeds that of nanospheres when particles are placed on an optimized spacer layer of <i>SiO₂, </i>for reasonable surface coverages of up to 25%. Our analysis shows that for a large range of particle sizes, 60 - 100<i>nm</i>, enhancement in light absorption remains at a high level, near the optimum. This suggests a high level of fabrication tolerance which is important due to the chemical growth mechanism used for nanocube synthesis, as it consistently produces nanocubes in that range. Further, we note that efficiency enhancement by nanocubes is influenced by particle size, surface coverage, and spacer layer thickness much differently than that for a spherical geometry, thus our study focuses on the optimization of the nanocube parameters. We show that 80nm nanocubes on a 25<i>nm SiO₂ </i>spacer layer realize ~ 24% enhancement in light absorption compared to an identical particle-free cell. Finally, we present both the numerical and experimental results for silicon solar cells coated with nanocube arrays.