Magnesium Fluoride Electron-Selective Contacts for Crystalline Silicon Solar Cells

Yimao Wan*, Chris Samundsett, James Bullock, Thomas Allen, Mark Hettick, Di Yan, Peiting Zheng, Xinyu Zhang, Jie Cui, Josephine McKeon, Ali Javey, Andres Cuevas

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    201 Citations (Scopus)

    Abstract

    In this study, we present a novel application of thin magnesium fluoride films to form electron-selective contacts to n-type crystalline silicon (c-Si). This allows the demonstration of a 20.1%-efficient c-Si solar cell. The electron-selective contact is composed of deposited layers of amorphous silicon (∼6.5 nm), magnesium fluoride (∼1 nm), and aluminum (∼300 nm). X-ray photoelectron spectroscopy reveals a work function of 3.5 eV at the MgF2/Al interface, significantly lower than that of aluminum itself (∼4.2 eV), enabling an Ohmic contact between the aluminum electrode and n-type c-Si. The optimized contact structure exhibits a contact resistivity of ∼76 mω·cm2, sufficiently low for a full-area contact to solar cells, together with a very low contact recombination current density of ∼10 fA/cm2. We demonstrate that electrodes functionalized with thin magnesium fluoride films significantly improve the performance of silicon solar cells. The novel contacts can potentially be implemented also in organic optoelectronic devices, including photovoltaics, thin film transistors, or light emitting diodes.

    Original languageEnglish
    Pages (from-to)14671-14677
    Number of pages7
    JournalACS applied materials & interfaces
    Volume8
    Issue number23
    DOIs
    Publication statusPublished - 15 Jun 2016

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