Feasibility of improving front metallization lines for photovoltaic devices

Screen-printing is widely used today as the metallization technique for industrial solar cells. Due to the limitation of the process, screen-printed contacts have low aspect ratio and low line conductivity that lower the efficiency of the solar cells. To address this issue, we developed a two-layer metallization process that deposited copper (Cu) as current-carrying electrodes by light induced electroplating (LIP) technique on thin screen-printed silver (Ag) paste seed layers. A nickel (Ni) layer was also deposited by LIP as the barrier and Cu adhesion layer. A series of trials with various electrolyte compositions as well as different organic additives were investigated as part of this work. By optimizing the thickness of the plated Ni and Cu layers, line resistivity of 1.75 µOhm-cm as low as that of bulk Cu, 1.68 µOhm-cm and bulk silver (Ag), 1.59 µOhm-cm was achieved.