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Dipl.-Chem. Mathias Kamp

 

Room: Fraunhofer Institut ISE: I-208

Telephone: +49 (0) 7 61/45 88-2083

Fax: +49 (0) 7 61/45 88-92 50

e-Mail: Mathias.Kamp@ise.fraunhofer.de

 

Keywords:  Plating and anodizing processes, silicon solar cells

 

 

Figure1.jpgThe topic of my work is the development of novel metallization technologies for n-type based silicon solar cells. The work is a collaboration of the Fraunhofer ISE and the University of Freiburg. Especially for advanced crystalline silicon solar cell concepts, for instance IBC (interdigitated back contact) solar cells, plating processes are an economical option to produce current conductors. Electrical separation between p- and n-type conductors can be achieved economically by an anodizing process. Anodic oxidation is applied locally by using screen printing or dispensing processes (Fig. 1) [1]. The seed metal which forms the electrical and mechanical contact to the doped silicon areas is evaporated aluminum in most instances. To ensure a sufficient current transport, aluminum has to be thickened with another conductor.
Fig. 1: Schematic approach of in-situ anodizing by dispensing.[1]

In order to realize this, zincating processes are applied to make the aluminum plateable. This way, well-adhering Al-Ni-Cu metal stacks are formed (Fig 2). The thickened aluminum current conductors are increased in lateral conductivity by this approach. This results in a fill factor increase and consequently in a higher solar cell efficiency. Small area solar cells (20x20 mm) are enhanced by 0.6 % to an absolute efficiency of 20.4 % [2-4]. The approach has been tested for large area solar cell test structures resulting in a good homogeneity of deposition (Fig 3).

Figure2.jpg
Figure3.jpg
Fig. 2: Cross-section SEM image of Al-Ni-Cu stack. Aluminum is activated by zincate process and plated by nickel and copper.
Fig. 3: Photography of a solar cell test structure (125x125 mm) with evaporated aluminum pattern, plated by nickel and copper.
Further solar cell concepts, for which electrochemical metal deposition processes are developed in the context of my work, are n-type solar cells with boron doped emitter. For this approach it is necessary to deposit nickel and copper electrochemically. The developed plating process, called FBP (forward bias plating), uses the diode characteristics of the solar cell. Efficiencies of 21.8 % solar cell efficiency are achieved [5]. Another topic of my work is plating for heterojunction solar cells, where plating on TCO (transparent conductive oxide) is one of the challenges [6]. The ionic liquid expertise of the University of Freiburg is used to transfer aluminum deposition to solar cell metallization.   
 


References:


  1.   Mathias Kamp, Axel Maywald, Jonas Bartsch, Raphael Efinger, Roman Keding, Markus Glatthaar, Stefan W. Glunz, Ingo Krossing, Electrochemical Contact Separation for PVD Aluminum Back Contact Solar Cells, Energy Procedia, Volume 67, April 2015, Pages 70-75, ISSN 1876-6102, http://dx.doi.org/10.1016/j.egypro.2015.03.289
  2.   Mathias Kamp, Jonas Bartsch, Gisela Cimiotti, Roman Keding, Ardiana Zogaj, Christian Reichel, Andre Kalio, Markus Glatthaar, Stefan Glunz, Zincate processes for silicon solar cell metallization, Solar Energy Materials and Solar Cells, Volume 120, Part A, January 2014, Pages 332-338, ISSN 0927-0248, http://dx.doi.org/10.1016/j.solmat.2013.05.035
  3.   Mathias Kamp, Jonas Bartsch, Roman Keding, Mike Jahn, Ralph Müller, Markus Glatthaar, Stefan W. Glunz, Ingo Krossing, Plating Processes on Aluminum and Application to Novel Solar Cell Concepts, Energy Procedia, Volume 55, 2014, Pages 679-687, ISSN 1876-6102, http://dx.doi.org/10.1016/j.egypro.2014.08.044
  4.   Keding, R.; Stuwe, D.; Kamp, M.; Reichel, C.; Wolf, A.; Woehl, R.; Borchert, D.; Reinecke, H.; Biro, D., "Co-Diffused Back-Contact Back-Junction Silicon Solar Cells without Gap Regions," Photovoltaics, IEEE Journal of , vol.3, no.4, pp.1236,1242, Oct. 2013, doi: 10.1109/JPHOTOV.2013.227438
  5.   Jonas Bartsch, Mathias Kamp, Dominik Hartleb, Carolin Wittich, Andrew Mondon, Bernd Steinhauser, Frank Feldmann, Armin Richter, Jan Benick, Markus Glatthaar, Martin Hermle, Stefan W. Glunz, 21.8% Efficient n-type Solar Cells with Industrially Feasible Plated Metallization, Energy Procedia, Volume 55, 2014, Pages 400-409, ISSN 1876-6102, http://dx.doi.org/10.1016/j.egypro.2014.08.116
  6.  Ankit Khanna, Kurt-Ulrich Ritzau, Mathias Kamp, Aleksander Filipovic, Christian Schmiga, Markus Glatthaar, Armin G. Aberle, Thomas Mueller, Screen-printed masking of transparent conductive oxide layers for copper plating of silicon heterojunction cells, Applied Surface Science, Volume 349, 15 September 2015, Pages 880-886, ISSN 0169-4332, http://dx.doi.org/10.1016/j.apsusc.2015.05.085