Nanoparticle-enhanced light trapping in thin-film silicon solar cells

A systematic investigation of the nanoparticle-enhanced light trapping in thin-film silicon solar cells is reported. The nanoparticles are fabricated by annealing a thin Ag film on the cell surface. An optimisation roadmap for the plasmon-enhanced light-trapping scheme for self-assembled Ag metal nanoparticles is presented, including a comparison of rear-located and front-located nanoparticles, an optimisation of the precursor Ag film thickness, an investigation on different conditions of the nanoparticle dielectric environment and a combination of nanoparticles with other supplementary back-surface reflectors. Significant photocurrent enhancements have been achieved because of high scattering and coupling efficiency of the Ag nanoparticles into the silicon device. For the optimum light-trapping scheme, a short-circuit current enhancement of 27% due to Ag nanoparticles is achieved, increasing to 44% for a "nanoparticle/magnesium fluoride/diffuse paint" back-surface reflector structure. This is 6% higher compared with our previously reported plasmonic short-circuit current enhancement of 38%.