Light trapping properties of metallic gratings on wafer-based silicon solar cells

摘要

Optical properties of arrays of silver nanowires, fabricated on the front surface of flat wafer-based Si solar cells, have been investigated for light trapping purposes. Numerical EM field simulations have been performed to optimize the grating layout with the aim to maximize photogeneration in the device. External Quantum Efficiency and front surface reflectance spectra have been measured and compared to simulations. The designed nanostructures result to be not able to provide a global efficiency enhancement due to higher incoupling losses compared to reference cells. Nevertheless the gratings improve the Internal Quantum Efficiency over a wide spectral range in the NIR due to the redistribution of the absorption profile in areas of the device characterized by high carriers collection probability.