Water spitting is one of the most import methods to harvest solar energy. Hematite is a promising photoanode material. However

the diffusion length (20 nm) of the photogenerated hole in the hematite is much shorter than the photon penetration depth (120 nm at 550 nm wavelength) which causes significant recombination losses and thus

low solar to hydrogen conversion efficiency. A hematite/Ag nanohole array ultrathin film absorber is presented. The hemate layer is only 20 nm thick and has strong visible light absorption which contributes to a 238% enhancement in the photocurrent density compared with a bare hematite layer water splitting cell. The strong absorption properties are due to ultrathin film interference resonances and localized surface plasmon resonances. These absorption resonances can also be applied for solar photovoltaic cells employing semiconductors with poor photogenerated carrier transport properties.