Simple single-photomask process for fabrication of high-efficiency multicrystalline silicon solar cells

摘要

We have developed a simplified process sequence for fabrication of high-efficiency multicrystalline silicon (mc-Si) solar cells. Photolithography is required only to define the evaporated metal gridlines. We use this fast turn-around, high-yield baseline process to evaluate different mc-Si materials and new processing procedures. The process uses a one-step emitter diffusion/drive-in and an aluminum-alloyed back surface field to provide a well-passivated cell with excellent blue and red response. Laser-scribed cell-isolation grooves are used to define both moderate-area (4 cm(sup 2)) and large-area (42 cm(sup 2)) cells. We have been able to achieve minority-carrier diffusion lengths well over 300 (mu)m in 2-(Omega)cm mc-Si material and have achieved efficiencies of 16.2% in 4-cm(sup 2) cells. This was accomplished without hydrogenation to passivate bulk defects or texturing to reduce reflectance. By using the same fabrication process for both small-area and large-area cells, we intend to determine and minimize the effect of areal inhomogeneities on large-area mc-Si cell performance.