Periodic silver nanoparticles fabricated with soft-stamp nanoimprint on silicon solar cells

The fabrication of periodic silver nanoparticle arrays has been successfully demonstrated by adapting nanoimprint lithography. This method has the advantage of good control on the size and shape of the particles and other advantages such as low fabrication cost, large coverage and robust process. In this study, we varied the Ag nanoparticle shape by a simple annealing process. The diameter to height ratio was varied from 1:0.3 to 1:1.7. We applied the periodic Ag nanoparticles on the front of a 2mm c-Si cell, which showed EQE enhancement over long wavelength region (750nm to 1100nm), but also reduction in the short wavelength region (380nm to 750nm). However, by putting the periodic Ag nanoparticles on the rear, the reduction in the short wavelength region is eliminated while still maintaining the enhanced EQE in the long wavelength region. A photocurrent increment of 11% over the spectral region is observed with an EQE enhancement of 300% at 1050nm