The electronic structure of a bi-layer hole extraction contact consisting of nickel oxide (NiOx) and molybdenum trioxide (MoO3) is determined via ultraviolet and X-ray photoemission spectroscopy. The bi-layer presents ideal energetics for the extraction of holes and suppression of carrier recombination at the interface. The application of the NiOx/MoO3 bi-layer as the anode of organic bulk heterojunction solar cells based on PCDTBT/PC71BM leads to improved device performance, which is explained by an intricate charge transfer process across the interface.