Laser induced quasi-periodical microstructures with external field modulation for efficiency gain in photovoltaics

The overall reflectivity of silicon is decreased by 10% altering the surface topology by ultra-short pulsed laser ablation and resulting in an efficiency increase of solar cells. The size of quasi-periodical μm-structures on the surface can be defined by the applied laser parameters. The topology is additionally adapted in size and distance of the microstructures at constant laser parameters with a specifically applied external electrical field leading to a cone-like microstructure with an adjustable light-trapping geometry. On large scale multicrystalline silicon solar wafers with a laser generated μm-scale surface topology were processed into cells with an absolute efficiency gain.