Design and fabrication of a light trapping method for photovoltaic devices based on plasmonic gratings

The integration of silver 1D gratings as light trapping method on both wafer-based and thin-film flat silicon solar cells has been investigated by EM field numerical simulations. The far field scattering properties or the near field enhancement and coupling to guided modes have been respectively studied in combination with thick (200 μm) and thin (100 nm) absorber layers. The optimization of the layout shows that arrays of metallic nanowires placed on the front surface improve light harvesting in thin film devices but provide absorption enhancement only for TM polarized light in wafer based devices. The designed gratings have been fabricated with a process based on Laser Interference Lithography suitable to nanopattern large area substrates and able to control the duty cycle. Optical characterizations of the samples validate the modelling results.