Nonanethiol capped gold nanoparticles were firstly used to modify the surface of MoO 3 thin films in order to fabricate the MoO 3/Au composite thin film. Absorption experiments and XPS measurements were used to investigate the effect of Au nanoparticles on the photochromic properties of the composite thin film. According to the XPS measurements, the binding energy for the valence band(O 2p ) of the composite thin films decreased. The experimental results of absorbance showed that the photochromic efficiency for the composite thin films became at least as two times as that of MoO 3 thin films. The mechanism of enhancement can be explained by the band energy theory of semiconductor. The Schottky barrier formed at the interface prolonged the electron hole pair separation lifetime and resulted in the enhancement of the photochromic efficiency.
