High‐performance hole‐selective V 2 O X / SiO X / NiO X contact for crystalline silicon solar cells

High work function vanadium oxide (V 2 O X , X < 5) is expected to induce strong upward band bending at crystalline silicon ( c ‐Si) surface thus selectively collect photogenerated hole‐carriers. However, the performance of c ‐Si solar cells employing V 2 O X ‐based hole‐selective contacts is still under expectation. Herein, we improve the hole‐selectivity of V 2 O X in combination with NiO X . The innovative V 2 O X /NiO X stack shows reduced contact resistivity but deteriorated minority carrier lifetime due to undesired interfacial reaction between V 2 O X and NiO X . Inserting an ultrathin SiO X interlayer suppresses the reaction and preserves the high work function of V 2 O X . A remarkable power conversion efficiency of 22.03% (fill factor of 83.07%) was achieved on p ‐type c ‐Si solar cells featuring a full‐area V 2 O X /SiO X /NiO X rear contact, which is so far the highest value reported for V 2 O X ‐based selective contacts. Our work highlights the significance of implementing p ‐type transition‐metal‐oxides to boost the selectivity of V 2 O X and the like.