Selectivities of an all-wet-processed electrode film on ITO, ZnO, SiNx and doped Si for solar cell applications

Abstract

We investigated the role of Ni/Cu metallization and the characteristics of selective thin-film deposition on the Indium tin oxide (ITO), ZnO, SiNx and doped Si surfaces of a silicon solarcell electrode. We propose Ni/Cu metallization as an alternative to silver screen-printing. Our method, called the selective electrode formation (SEF) process, utilizes a low-cost, streamlined wet chemical process. Metallization was confirmed to occur on the Si electrode with adhesion through Pd activation. Ni, which hinders Cu diffusion, was then selectively deposited from a NaH2PO2 based nickel solution, and Cu, the main electrode material, was deposited from a HCHObased copper solution. Ni/Cu was deposited on the ZnO, ITO, or SiNx film. The deposition and the heat treatment of Ni and Cu were successfully performed on a substrate consisting of a patterned n+-doped wafer with POCl3 by maintaining the same steady process conditions as in process.