Varying the layer structure in multicrystalline LLC-silicon thin-film solar cells

Multicrystalline silicon thin-film solar cells with grains exceeding 100 μm were prepared by layered laser crystallization. The layer system is generated in two steps. In the first step a multicrystalline seed layer is fabricated on a low cost glass substrate. This is achieved by depositing a-Si followed by scanning a diode laser beam for crystallization. In a second step this seed layer is epitaxially thickened by electron beam evaporation of a-Si combined with repeatedly applying pulses of an excimer laser. p⁺pn⁺ and p⁺nn⁺ superstrate cells with 2 μm thick absorber were prepared with different doping levels and different thickness of the seed layer. Without reflector these cells, after hydrogen passivation, delivered Voc up to 514 mV and Isc of 17.5 mA/cm² if deposited directly onto the glass substrate. With an additional SiNx antireflection layer Isc reached 20 mA/cm².