Improved adhesion of Ni/Cu/Ag plated contacts with thermally formed nickel silicon interface for C-SI solar cells

In this work the copper (Cu) conducting electrode was appraised as an alternative to standard screen printed silver (Ag) front contacts. Laser ablation and photolithography based wet chemical etching were adapted to pattern and analyze adhesion for reliable crystalline silicon (C-Si) solar cell technology. Nickel (Ni) surface treatment after the sintering process contributed to an improved Cu plating with an adhesive Ni-Cu interface. The soldering process for the pull tab adhesion test has an impact on adhesion strength and could reduce the overall value. Smoother surfaces resulted in lower adhesion values in comparison to rough surfaces. Excellent adhesion greater than wafer breakage force with an average value of 1.72 N/mm and maximum adhesion strength of 4.6 N/mm on laser-ablated surfaces were achieved.