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Proceedings Paper

Ultrafast laser scribing of transparent conductive oxides in Cu(In,Ga)Se2 solar cells via laser lift-off process: the control of laser-induced damage
Author(s): Aiko Narazaki; Tadatake Sato; Hiroyuki Niino; Hideyuki Takada; Kenji Torizuka; Jiro Nishinaga; Yukiko Kamikawa-Shimizu; Shogo Ishizuka; Hajime Shibata; Shigeru Niki
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Paper Abstract

For higher cell-to-module efficiency in Cu(In,Ga)Se2 (CIGS) thin-film solar cells, it is important to reduce the loss of active area due to integrated connection. The integrated connection contains three scribing processes: P1 (back contact insulation), P2 (electrical connection) and P3 (transparent conductive oxide, shortly TCO front contact insulation). In this work, we focused on ultrashort-pulse laser scribing (λ=1034 nm, Δτ=300 fs) of TCO via lift-off process as damage-less P3 scribing of CIGS thin-film solar cells. The lift-off of TCO was caused by laser ablation of only an upper part of CIGS light-absorbing layer. The dependence of lift-off behavior on the laser pulse energy and TCO film thickness has been investigated. It was observed that the lift-off of TCO formed a heat-affected zone (HAZ) with a thickness up to 250 nm beneath the trench bottom, where the CIGS experienced to melt. Further, thinner TCO film required lower laser energy threshold for the TCO lift-off, which is favorable to higher solar cell efficiency due to smaller HAZ. Using the TCO liftoff as P3, a submodule with an active area of approximately 3.5 cm2 made by all laser scribing exhibited the conversion efficiency of 11.6 %. After post-annealing at 85 °C for 15 h in vacuum for recovering laser-induced damages, the efficiency was successfully improved to 15.0 %, which is comparable to mechanically-scribed one.

Paper Details

Date Published: 20 February 2017
PDF: 9 pages
Proc. SPIE 10091, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII, 100911E (20 February 2017); doi: 10.1117/12.2266895
Show Author Affiliations
Aiko Narazaki, National Institute of Advanced Industrial Science and Technology (Japan)
Tadatake Sato, National Institute of Advanced Industrial Science and Technology (Japan)
Hiroyuki Niino, National Institute of Advanced Industrial Science and Technology (Japan)
Hideyuki Takada, National Institute of Advanced Industrial Science and Technology (Japan)
Kenji Torizuka, National Institute of Advanced Industrial Science and Technology (Japan)
Jiro Nishinaga, National Institute of Advanced Industrial Science and Technology (Japan)
Yukiko Kamikawa-Shimizu, National Institute of Advanced Industrial Science and Technology (Japan)
Shogo Ishizuka, National Institute of Advanced Industrial Science and Technology (Japan)
Hajime Shibata, National Institute of Advanced Industrial Science and Technology (Japan)
Shigeru Niki, National Institute of Advanced Industrial Science and Technology (Japan)


Published in SPIE Proceedings Vol. 10091:
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXII
Beat Neuenschwander; Costas P. Grigoropoulos; Tetsuya Makimura; Gediminas Račiukaitis, Editor(s)

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