Electroplated Al as the front electrode in crystalline-Si solar cells

This paper reports aluminum (Al) electroplating as the metallization technique for the front finger electrode on n-type silicon (Si) in crystalline-Si solar cells. The development of the Al electroplating process is motivated by the limited reserves of silver (Ag) on this planet and the industry-wide push to reduce Ag usage for cost control. The new metallization process consists of: (1) patterning the silicon nitride (SiNx) layer for front electrode; (2) depositing a nickel (Ni) seed layer into the opening; (3) electroplating self-aligned Al onto the Ni seed layer and (4) annealing the Al/Ni electrode in air at ~200°C. This temperature is far below the typical firing temperatures for commercial Al pastes. The new metallization process has been integrated into commercial p-type monocrystalline Si solar cells from Hareon Solar. An all-Al Si solar cell, with an electroplated Al front electrode and a screen-printed Al back electrode, has been demonstrated. The cell has a size of 2.54×2.54 cm2, with efficiencies approaching 15% demonstrated.