Toward Annealing-Stable Molybdenum-Oxide-Based Hole-Selective Contacts For Silicon Photovoltaics
S. Essig, J. Dréon, E. Rucavado, M. Mews, T. Koida, M. Boccard, J. Werner, J.Geissbühler, P. Löper, M. Morales-Masis, L. Korte, S. De Wolf, C. Ballif
Sol. RRL, volume 2, issue 4, 1700227, (2018)
Heterojunction, Hydrogen, Metal oxide, Silicon solar cells
Molybdenum oxide (MoOX) combines a high work function with broadband optical transparency. Sandwiched between a hydrogenated intrinsic amorphous silicon passivation layer and a transparent conductive oxide, this material allows a highly efficient hole‐selective front contact stack for crystalline silicon solar cells. However, hole extraction from the Si wafer and transport through this stack degrades upon annealing at 190 °C, which is needed to cure the screen‐printed Ag metallization applied to typical Si solar cells. Here, we show that effusion of hydrogen from the adjacent layers is a likely cause for this degradation, highlighting the need for hydrogen‐lean passivation layers when using such metal‐oxide‐based carrier‐selective contacts. Pre‐MoOX‐deposition annealing of the passivating a‐Si:H layer is shown to be a straightforward approach to manufacturing MoOX‐based devices with high fill factors using screen‐printed metallization cured at 190 °C.
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