Essig, S.; Dréon, J.; Rucavado, E.; Mews, M.; Koida, T.; Boccard, M.; Werner, J.; Geissbühler, J.; Löper, P.; Morales-Masis, M.; Korte, L.; de Wolf, S.; Ballif, C.:
Toward Annealing-Stable Molybdenum-Oxide-Based Hole-Selective Contacts For Silicon Photovoltaics. Solar RRL 2 (2018), p. 1700227/1-5
10.1002/solr.201700227
Open Accesn Version
Abstract:
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.