LIFT and laser sintering of silver paste for silicon solar cells metallization

Laser Induced Forward Transfer (LIFT) is a promising and innovative method for printing and metallizing electrodes using metallic inks and pastes for the PV industry. LIFT is a laser direct write technique that allows the selective transfer of a wide range of materials in different ranges of viscosity, from solid materials to pure Newtonian fluids In this work, we demonstrate the possibility of define a metallization process compatible with high efficiency solar cells using a two step laser-based process. First a commercial silver paste is printed using a Laser Induced Forward Transfer Process (LIFT) to define the metallization pattern onto the photovoltaic device using a ns-pulsed laser working at 532 nm. In the second step a CW green laser is used to sinter and functionalize the previously deposited contact. A comprehensive discussion of the influence of laser parameters (pulse energy, spot diameter, scanning speed, overlapping,…) on the morphology and electrical characteristics of the printed and sintered lines are included. As final proof of concept, we present results of printed metallization patterns onto silicon heterojunction silicon solar cells.