Optimized design of silver nanoparticles for broadband and high efficiency light trapping in thin film solar cells

This paper reports a high-efficiency approach to improve the photoelectric-conversion efficiency of thin-film solar cells by plasmonic scattering and local near-field amplification of silver nanoparticles. We employ a three-dimensional (3D) electromagnetic model and use the finite-difference time-domain (FDTD) and rigorously coupled-wave analysis methods to investigate the interaction of light with such a metallic particle. The numerical results show that the absorption and scattering spectra depend upon the properties of the embedded particles and the refractive index of the surrounding material. Strong redshifts and high-order modes are observed in the response spectrum with the increase of the particle size and the refractive index of the surrounding material. With an optimized design having P = 200, H = 135, and D = 70 nm, the performance of cell device is improved over a broad spectral range. Moreover, some of the absorption, in the resonance region, is beyond the Yablonovitch limit. The corresponding light-generated photocurrent is increased from 14.2 mA/cm(2) to 18.3 mA/cm(2), with a 28.9% enhancement compared with conventional cells with antireflective coatings (ARCs).