ECN publication
Title:
Depth-selective laser ablation for monolithic series interconnection of flexible thin-film silicon solar cells
 
Author(s):
 
Published by: Publication date:
ECN Solar Energy 21-9-2009
 
ECN report number: Document type:
ECN-M--09-022 Conference Paper
 
Number of pages: Full text:
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Presented at: 24th European Photovoltaic Solar Energy Conference and Exhibition, Hamburg, Germany, 21-25 september 2009.

Abstract:
ECN is currently developing the technology and setting up a pilot line for the production of single junction and tandem solar cells based on microcrystalline and amorphous silicon on steel foil substrates. To allow monolithic series interconnection on these electrically conducting substrates, an insulating layer is required. In the presented module concept, first all layers of the solar cell are deposited, and after that series interconnection can be realized in one process step by three depth-selective laser scribes (P1, P2, and P3) which are then filled by insulating and electrically conductive inks. We present here the latest status of our laser process development on state-of-the art solid state lasers with three different wavelengths. To gain more insight into the depth selectivity of the process, the ablation thresholds of the different layers involved have been determined. Then, the laser parameters have been systematically varied, yielding a pulse energy / spot overlap matrix. Also multi-pass scribing, (2 or more scribing lines on top of each other) has been investigated. Confocal microscopy combined with optical microscopy, SEM and EDX are used as the main tool to analyse the obtained laser scribes.


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