Implantation-based passivating contacts for crystalline silicon front/rear contacted solar cells

Gianluca Limodio, Guangtao Yang, Yvar De Groot, Paul Procel, Luana Mazzarella, Arthur W. Weber, Olindo Isabella, Miro Zeman

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
63 Downloads (Pure)

Abstract

In this work, we develop SiOx/poly-Si carrier-selective contacts grown by low-pressure chemical vapor deposition and boron or phosphorus doped by ion implantation. We investigate their passivation properties on symmetric structures while varying the thickness of poly-Si in a wide range (20-250 nm). Dose and energy of implantation as well as temperature and time of annealing were optimized, achieving implied open-circuit voltage well above 700 mV for electron-selective contacts regardless the poly-Si layer thickness. In case of hole-selective contacts, the passivation quality decreases by thinning the poly-Si layer. For both poly-Si doping types, forming gas annealing helps to augment the passivation quality. The optimized doped poly-Si layers are then implemented in c-Si solar cells featuring SiO2/poly-Si contacts with different polarities on both front and rear sides in a lean manufacturing process free from transparent conductive oxide (TCO). At cell level, open-circuit voltage degrades when thinner p-type poly-Si layer is employed, while a consistent gain in short circuit current is measured when front poly-Si thickness is thinned down from 250 to 35 nm (up to +4 mA/cm2). We circumvent this limitation by decoupling front and rear layer thickness obtaining, on one hand, reasonably high current (JSC-EQE = 38.2 mA/cm2) and, on the other hand, relatively high VOC of approximately 690 mV. The best TCO-free device using Ti-seeded Cu-plated front contact exhibits a fill factor of 75.2% and conversion efficiency of 19.6%.

Original languageEnglish
Pages (from-to)403-416
Number of pages14
JournalProgress in Photovoltaics: research and applications
Volume28
Issue number5
DOIs
Publication statusPublished - 2020

Keywords

  • doping
  • ion implantation
  • passivating contacts
  • poly-silicon
  • silicon solar cells

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