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 (VO x ) deposited by atomic layer deposition (ALD) is investigated and optimized as a potential hole‐selective contact for c ‐Si solar cells. ALD VO x films are demonstrated to simultaneously offer a good surface passivation and an acceptable contact resistivity (ρ c ) on c ‐Si, achieving a best contact recombination current density ( J 0 ) of ≈40 fA cm −2 and a minimum ρ c of ≈95 mΩ.cm 2 . Combined with a high work function of 6.0 eV, ALD VO x films are proven to be an effective hole‐selective contact on c ‐Si. By the implementation of hole‐selective VO x 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 VO x as a stable hole‐transport layer for photovoltaic devices, with applications beyond c ‐Si, such as perovskite and organic solar cells.