Nanoparticle-Enhanced Plasmonic Light Absorption in Thin-Film Silicon Solar Cells

In this paper, numerical simulations are performed for different configurations of plasmonic and dielectric scatters for the purpose of enhancing light absorption in Si solar cells. The numerical model is developed on the basis of FDTD solution of the transient Maxwell equations. Results show that for Ag nanoparticles, the optimal light absorption is achieved with a particle radius of 75 nm and particle spacing of 3r to 5r. For dielectric SiO₂ nanoparticles, a closely packed configuration with particle size of 50 nm in radius yields the optimal light absorption. The enhancement for both optimal cases is similar, measured by the short currents. Simulations with SiO₂ nanoparticles embedded into Si at various different positions were conducted and results suggest that when the SiO₂ particle buried half-way into the Si substrate, the light absorption enhancement is better than that with the particles placed at the top or embedded completely inside the Si layer. Analysis of a new design, with Ag atop the surface of and SiO₂ inside the Si layer, was also performed. The results suggest that such a combined configuration produces the best light absorption enhancement among all those studied, achieving an 80% improvement compared with bare thin film.