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 similar to 200 degrees 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 2.54x2.54 cm(2), with efficiencies approaching 15% demonstrated.