[14p-P21-1~27] 13.10 Compound solar cells

[14p-P21-16] Preparation of CIGS Thin-Film Solar Cells by All Laser-Scribing

〇Aiko Narazaki¹, Tadatake Sato¹, Hiroyuki Niino¹, Hideyuki Takada¹, Kenji Torizuka¹, Jiro Nishinaga¹, Yukiko Kamikawa¹, Shogo Ishizuka¹, Hajime Shibata¹, Shigeru Niki¹ (1.AIST)

Keywords:CIGS thin-film solar cell, Laser scribing

Cu(In,Ga)Se₂ (CIGS) is one of the most promising thin-film solar cells because of excellent properties like high efficiency and high tolerance for exposure to sunlight. Large-area solar cells are divided into multi small segments, which are interconnected in series in order to reduce the resistance loss. The interconnection is accomplished by three scribing processes called P1, P2, and P3. The P1 scribes a back contact layer next to a substrate for isolating segments. The P2 is necessary to connect electrically the back and front contact layers of adjacent cells for the series interconnection. Finally, the P3 scribe makes the electrical isolation in the front contact layer between adjacent cells. Although mechanical scribing is still a main stream in the industrial fabrication of CIGS solar cells, laser scribing has been attracting much attention due to rapid and selective removal of films. Additionally, in the nature of non-contact process, the laser scribing has great potential for reducing trench width and dead-area. However, the laser scribing of CIGS solar cells was often accompanied by a thermal damage, decreasing the cell efficiency.
In this work, we tried to suppress such thermal effect by the P3 scribe using a femtosecond pulsed laser, that removed only transparent conductive oxide (TCO) and buffer layers, and post-annealing. As a result, we successfully kept the high solar cell efficiency after all P1-P3 laser scribing.