Bessel beam laser-scribing of thin film silicon solar cells by ns pulsed laser

Abstract

The thin film solar cells have attracted wide attentions for its low implementation cost and representative flexibilities such as selectivity of materials and fabrication conditions. On the thin film solar cells, width of the grooves of pattern 1, 2 and 3 are important factors to determine its efficiency and cost. In this study, as P1 fabrication process, ablation experiments of Transparent Conductive Oxide (TCO) coating on glass substrates of thin film solar cells are conducted using Bessel beam nanosecond laser pulse. The purpose is to assess the capability of the Bessel beam in laser scribing of thin film solar cells from the glass side. In order to fulfill this purpose, a Gaussian beam of 1064 nm nanosecond Nd:YAG was shaped into Bessel beam with few-micrometers beam width, using fluidic optical device. The Bessel beam, is used to backside laser ablation of a thin film. The function of the optical system and products fabricated with Bessel beam are compared with those of Gaussian beam. Experimental results show that: in the single pulse ablation, the vias ablated by Bessel beam have smaller variations in diameter and depth than those of Gausian beam at the same laser spot and peak fluence level. Furthermore, a few micrometer wide, perfectly isolated groove could be fabricated with Bessel beam. The paper concludes with suggestions for future research and potential application.

Keywords

• bessel beam
• back-side scribing
• tco
• solar cell