Characterization and module integration of full electroplated contacts on silicon solar cells

Abstract For the fabrication of high efficiency solar cells a full electroplated metallization process is beneficial. In this paper light induced plating (LIP) of thin Nickel seed layers and subsequent Silver metallization has been processed. The antireflective coating is opened by laser chemical doping (LCP). The subsequent front contact was formed by a Nickel/Silver stack deposited by light induced plating. To make electroplating industrial feasible high deposition rates are required. However, high plating rates can influence specific conductivity and uniformity in a negative way. Thus, the line conductivity which is strongly determined by the homogeneity and the morphology of the plated fingers was investigated. To improve these limiting factors the effect of current density and organic additives was investigated in terms of finger resistances and microscope pictures. In order to achieve a good uniformity and conductivity on thin fingers, an organic additive which acts as leveling agent was applied. This leveler inhibits electrodeposition in areas of high electrical field. Therefore, different textures, plating rates and concentrations of leveling agents are compared. Furthermore, different methods for interconnection of electroplated solar cells are discussed. In terms of adhesion, the first results show that bonding of the electroplated busbars is most suitable for interconnection. With bonding, a peel of strength of more than 1,5N on the whole area can be achieved. Also, the relative efficiency loss of bonded cells is in an adequate range with 1.8%.