A new technique for solar cells improvement in “Nature Energy”
Published on 18/10/2018
On the September edition of Nature Energy, the monthly peer-reviewed scientific journal, three researchers from the Luxembourg Institute of Science and Technology (LIST) - Santhana Eswara, Tom Wirtz and Nathalie Valle - co-authored a paper with Swiss and Japanese colleagues from the École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, CSEM, Switzerland, and the National Institute of Advanced Industrial Science and Technology (AIST), Japan. While Santhana Eswara and Tom Wirtz brought their expertise in Advanced Instrumentation for Ion Nano-Analytics (AINA), Nathalie Valle is specialised in materials characterization using Secondary Ion Mass Spectrometry (SIMS).
A new method to improve efficiency
Within this paper, entitled “A passivating contact for silicon solar cells formed during a single firing thermal annealing” the authors presented a new cost-effective method for the formation of passivating contacts for silicon solar cells. They highlighted that solar cells whose passivating contacts - indispensable for achieving high conversion efficiency in crystalline-silicon solar cells - have been formed thanks to a single post-deposition annealing step can offer various advantages.
First the researchers could clearly demonstrate that this new technique allows the final solar cells an open circuit voltage of 698 mV and an efficiency of 21.9%, Second, they show how it could be a drop-in replacement for today’s rear contacts based on locally opened dielectric passivation stacks. Therefore, the new method is well-positioned to be adopted by large-scale manufacturers.
Environmental and economical improvement of solar cells
The paper has been written as part of the “Nanostructured passivating contacts for high efficiency crystalline silicon solar cells” (NACHOS) project which is led by Santhana Eswara in Luxembourg. Funded by the Luxembourg National Research Fund (FNR), and the Swiss National Science Foundation (SNSF), this project gathers LIST and EPFL’s researchers till 2021. For this project, LIST brings to EPFL its proven expertise in nanoscale analytical techniques and correlative microscopy methods for developing next-generation solar cells with better performance, a longer life and at a lower cost.
To do so, LIST researchers develop and apply high–resolution high-sensitivity techniques combining Secondary Ion Mass Spectrometry (SIMS) and Electron Microscopy for photovoltaic and other applications. In parallel to valorising the new analytical techniques being developed at LIST, the LIST researchers analyse solar cells with novel architecture fabricated at EPFL. The insights drawn from analyses at LIST are then used to refine the fabrication technology.
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