Nanotechnology enhanced solar cells prepared on laser-crystallized polycrystalline thin films (<10 µm)

It is shown in this paper that indeed silicon nanotechnology can significantly improve the performance of solar cells made on low-cost materials like polycrystalline silicon (pc-Si) thin films formed on glass substrates. By proper engineering of the nanowires (cleaning of the metal contamination from the metal-assisted wet chemical etching and passivation by a-Si:H emitter as well as by an ultrathin Al2O3 tunnel layer on the emitter surface) and by proper design of the cell structure (superstrate configuration), the detrimental effects related to the nanowires can be avoided while the light trapping properties remain. In superstrate configuration with an Ag reflector, a prototype solar cell with efficiency of 10% has been realized on a pc-Si thin film with a thickness of only 8 µm formed on glass, resulting from an enhanced photocurrent due to light trapping by silicon nanowires. Further optimization steps are discussed and targeted to improve the efficiency and the performance of the solar cells.