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The Benefit of Ultra-High Minority Carrier Lifetime Silicon Wafers for High-Efficiency and Innovative Solar Cells
I. MacLellan, S. Sivoththaman, S. Zijlstra, J. Vedde, R. Kleiman, P. Dold, J. Olson, T. Hartmann, Z. Gao, K.C. Chang, T. Cadwell, J. Bodker, F. Faller
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Silicon Feedstock, Crystallisation and Wafering
Event: 32nd European Photovoltaic Solar Energy Conference and Exhibition
Session: 2DV.3.23
1044 - 1048
ISBN: 3-936338-41-8
Paper DOI: 10.4229/EUPVSEC20162016-2DV.3.23
0,00 EUR
Document(s): paper


Over the past 10 years, average PV cell efficiencies (multi/mono) have improved by ~ 3-5% absolute from about 15-18% on volume weighted average basis to about 18-23%, and costs at the cell level have been reduced by over a factor of 10. This has been driven by improvements in wafer quality, cell design and technologies, economies of scale and manufacturing equipment and processes. The need for high minority carrier lifetime in wafers historically has been limited due to the quality of the cell processing steps and the success of gettering techniques developed to improve poor quality material. However, with recent trends in moving advanced PV cell concepts (PERC-family, hetero- or tunnel-junction, etc.) into production, and continued growth of current high-efficiency solar cell production (IBC, HIT), wafer quality and specifically minority carrier lifetime may now be a limiting factor for further improvement of the cell efficiency. In the near future, wafer quality will become more important to fully exploit the current state-of-the-art technologies, and implementing even more advanced solar cell designs. Mono-crystalline wafers produced using the Float Zone (FZ) process are known to provide the highest lifetimes, but have so far been too expensive to produce. An innovative technology to produce cost-effective FZ wafers is being introduced in this paper. A pilot production line is currently being set up by Ubiquity Solar, USI, in Canada, to produce n- and p-type ingots and wafers.