Passivating contacts based on transition metal oxides (TMOs) have the potential to overcome existing performance limitations in high-efficiency crystalline silicon (c-Si) solar cells, which is a significant driver for continuing cost/Watt reductions of photovoltaic electricity. Herein, innovative stacks of Al-alloyed TiOx (AlyTiOx) and pure TiOx as transparent electron-selective passivating contacts for n-type c-Si surfaces are explored. An optimized stack of 2 nm AlyTiOx and 2 nm TiOx is shown to provide both record-quality surface passivation and excellent electrical contact, with a surface recombination current density prefactor J 0 of 2.4 fA cm−2 and a specific contact resistivity ρ c of 15.2 mΩ cm2. The performance of this innovative stack significantly exceeds previously reported values for pure or doped TiOx single layers, SiOx/TiOx stacks, a-Si:H/TiOx stacks, and other transparent contact technologies. Furthermore, an excellent efficiency of 21.9% is attained by incorporating the optimized stack as a full-area rear contact in an n-type c-Si solar cell. The findings set a new benchmark for the passivation performance of metal oxide-based passivating contacts, bringing it to a level on par with state-of-the-art SiOx/poly-Si contacts while greatly improving optical transparency.
- high efficiencies
- passivating contacts
- silicon solar cells
- silicon surface passivation
- transparent electron-selective contacts