Cost-effective thin film solar cell processing on multicrystalline silicon

Thin-film solar cells have been produced in a pilot-line making use of industrial techniques. Typical laboratory process steps such as P ₂O₅ solid-source diffusion, emitter etch-back, remote plasma hydrogenation, lithography, metal evaporation and lift-off, have been replaced by cost-effective techniques such as screen printing or POCl₃ diffusion, PECVD silicon nitride deposition and screen printing metallization and firing-through-nitride, respectively. The low-cost high-throughput techniques have been applied to epitaxial thin-film solar cells with success. Efficiencies of 12% have been obtained on 20 μm thin-film solar cells made in epitaxial layers on highly doped multicrystalline silicon substrates without making use of optical path length enhancement. The hydrogenation induced by the firing-through-nitride process passivates the bulk of the epitaxial cell but not to the same extent as a remote plasma hydrogenation in the laboratory-scaled process