LIFT metallization as an alternative to screen-printing for silicon heterojunction solar cells

Abstract

The electrical characteristics of solar cells are significantly influenced by the metallization process, making it a crucial step. Screen printing is the standard metallization technique, but there is an increasing interest in the development of methods that allow more versatility, higher process control, and a more efficient use of the expensive metallic pastes used. We focus here on the comparison between the standard screen-printing method, and Light-Induced Forward-Transfer (LIFT), a non-contact, very precise technique, able to transfer volumes down to picolitres. The high flexibility, using free-form designs that do not depend on any mask or physical support, and the efficient use of the metallic paste with almost no waste, are other characteristics that point out LIFT as a very promising alternative. In this paper we include the electric characterization of contacts, and solar silicon heterojunction (SHJ) cells metalized with both techniques. The results show a slightly better efficiency for the screen-printed cells, but good series resistance and fill factor values imply that LIFT is a promising alternative for device metallization.