Laser ablation and contact formation for Cu-plated large area C-silicon industrial solar cells

Abstract

In this work we demonstrate the successful implementation of laser ablation of SiN x ARC to contact high ohmic emitters up to 120 Ω/sq with an advanced metallization on large area substrates. We propose Suns-Voc measurements as a fast and effective method to characterize the potential laser damage. We look at the laser ablation factors that can compromise the solar cell performance and we see how to limit the damage that can jeopardize the device performance. We define the laser ablation process window for emitters of different resistivity ranging from a typical 60 Ω/sq emitter to a emitter of 140 Ω/sq. A point-contact contacting scheme is proposed that leads to an improved V oc of the solar cell. Finally we present results of the electrical characterization of large area solar cells. Efficiencies up to 18.7% are obtained on large area, 160 µm thick CZ silicon substrates.