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Key aspects for fabrication of p-type Cz-Si PERC solar cells exceeding 22% conversion efficiency

: Werner, S.; Lohmüller, E.; Saint-Cast, P.; Greulich, J.M.; Weber, J.; Schmidt, S.; Moldovan, A.; Brand, A.A.; Dannenberg, T.; Mack, S.; Wasmer, S.; Demant, M.; Linse, M.; Ackermann, R.; Wolf, A.; Preu, R.

Volltext urn:nbn:de:0011-n-4774690 (602 KByte PDF)
MD5 Fingerprint: 5e3c55bf403a8a3ec6fda5cca126398c
Erstellt am: 16.1.2018

Smets, A.:
33rd European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2017 : Proceedings of the international conference held in Amsterdam, The Netherlands, 25 September - 29 September 2017
München: WIP, 2017
ISBN: 978-3-936338-47-8
ISBN: 3-936338-47-7
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <33, 2017, Amsterdam>
Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()
PV Produktionstechnologie und Qualitätssicherung; Photovoltaik; Silicium-Photovoltaik; Dotierung und Diffusion; Oberflächen: Konditionierung; Passivierung; Lichteinfang; Kontaktierung und Strukturierung; Pilotherstellung von industrienahen Solarzellen; Messtechnik und Produktionskontrolle; silicon solar cell; PERC; monocrystalline; emitter; passivation

This paper gives a close-up insight into recent and future developments that are performed with industrial focus at Fraunhofer ISE’s PV-TEC pilot-line to increase the energy conversion efficiency of 6-inch p-type Czochralski- grown silicon (Cz-Si) passivated emitter and rear cells (PERC) to 22% and above. First, the current status of PERC solar cell fabrication allowing for conversion efficiencies up to 21.5% is discussed. Then, we examine four key aspects in detail that need to be considered for optimizing the cells’ front side to boost the cell efficiency to the 22% regime. We demonstrate selective emitter laser doping out of the phosphosilicate glass layer, which is formed by a gas phase phosphorus oxychloride diffusion process. After diffusion and wet-chemical emitter etch back, the field emitter features a very low saturation current density of only 31 fA/cm² (textured, SiNx-passivated). Specific contact resistances of 1 mΩcm2 confirm the low-resistance contacting of the laser-doped surfaces using a commercially available silver screen printing paste. Apart from developing an accurate alignment procedure to match laserstructured and screen-printed layouts, we have also optimized our single-step screen-printing process for finger widths of 38 μm at 16 μm height. Based on simulations we find that efficiencies up to 22.5% are possible when the optimized process routes are integrated into PERC solar cells.