Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells

Johannes Peter Seif, Antoine Descoeudres, Miha Filipič, Franc Smole, Marko Topič, Zachary Holman, Stefaan De Wolf, Christophe Ballif

Research output: Contribution to journalArticle

90 Scopus citations

Abstract

In amorphous/crystalline silicon heterojunction solar cells, optical losses can be mitigated by replacing the amorphous silicon films by wider bandgap amorphous silicon oxide layers. In this article, we use stacks of intrinsic amorphous silicon and amorphous silicon oxide as front intrinsic buffer layers and show that this increases the short-circuit current density by up to 0.43 mA/cm2 due to less reflection and a higher transparency at short wavelengths. Additionally, high open-circuit voltages can be maintained, thanks to good interface passivation. However, we find that the gain in current is more than offset by losses in fill factor. Aided by device simulations, we link these losses to impeded carrier collection fundamentally caused by the increased valence band offset at the amorphous/crystalline interface. Despite this, carrier extraction can be improved by raising the temperature; we find that cells with amorphous silicon oxide window layers show an even lower temperature coefficient than reference heterojunction solar cells (-0.1/°C relative drop in efficiency, compared to -0.3/°C). Hence, even though cells with oxide layers do not outperform cells with the standard design at room temperature, at higher temperatures-which are closer to the real working conditions encountered in the field-they show superior performance in both experiment and simulation.

Original languageEnglish (US)
Article number024502
JournalJournal of Applied Physics
Volume115
Issue number2
DOIs
StatePublished - Jan 14 2014

    Fingerprint

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Peter Seif, J., Descoeudres, A., Filipič, M., Smole, F., Topič, M., Holman, Z., De Wolf, S., & Ballif, C. (2014). Amorphous silicon oxide window layers for high-efficiency silicon heterojunction solar cells. Journal of Applied Physics, 115(2), [024502]. https://doi.org/10.1063/1.4861404