CIGS P1, P2, and P3 laser scribing with an innovative fiber laser

Abstract

We report for the first time production-quality P2 and P3 scribes in CIGS based solar cells using a nanosecond-domain industrial pulsed laser We also show how the same laser can be used to produce the P1 scribe, and report what we believe to be the first all-laser-scribed monolithically-integrated CIGS solar cells in which all scribes were made using the same laser, at the same 1064nm wavelength. This paper reports the results of a collaborative effort involving two national laboratories and two private companies, and focuses on the laser scribing processes. A paper describing the design and characterization of the solar cells has been published elsewhere in this journal [1]. The new laser-based P2 and P3 processes rely on a “brittle fracture material removal” mechanism whose material removal characteristics are somewhat similar to those of mechanical scribing in that the material is ejected from the surface in fragments. However, unlike mechanical scribing, the laser process produces highly regular and deterministic edges. The first cells produced showed poor conversion efficiency, mostly attributed to high series resistance. These cells then had additional AZO deposited on them, and the results improved dramatically. Finally, we show results obtained using conventional mechanical scribing for the P2 and P3 processes on cells which are in other respects almost identical. Initial results are similar to the laser-scribed results.