Atomic Layer Deposition of Vanadium Oxide as Hole-Selective Contact for Crystalline Silicon Solar Cells

High carrier recombination loss at the contact regions has become the dominant factor limiting the power conversion efficiency (PCE) of crystalline silicon (c-Si) solar cells. Dopant-free carrier-selective contacts are being intensively developed to overcome this challenge. In this work, vanadium oxide (VOx ) deposited by atomic layer deposition (ALD) is investigated and optimized as a potential hole-selective contact for c-Si solar cells. ALD VOx films are demonstrated to simultaneously offer a good surface passivation and an acceptable contact resistivity (ρc) on c-Si, achieving a best contact recombination current density (J 0) of ≈40 fA cm−2 and a minimum ρc of ≈95 mΩ.cm2. Combined with a high work function of 6.0 eV, ALD VOx films are proven to be an effective hole-selective contact on c-Si. By the implementation of hole-selective VOx contact, the state-of-the-art PCE of 21.6% on n-type c-Si solar cells with a high stability is demonstarted. These results demonstrate the high potential of ALD VOx as a stable hole-transport layer for photovoltaic devices, with applications beyond c-Si, such as perovskite and organic solar cells.