TiO_2-Loaded WO_3 Composite Films for Enhancement of Photocurrent Density

Titanium dioxide (TiO_2) loaded tungsten trioxide (WO_3) composite films are prepared by an E-beam vapor system. Associated with the existence of a heterojunction at the interface of TiO_2 and WO_3, the prepared TiO_2-WO_3 composite film shows enhanced photocurrent density, four times than the pure WO_3 film illuminated under xenon lamp, and higher incident-photon-to-current conversion efficiency. By varying the initial TiO_2 film thickness, such composite structures could be optimized to obtain the highest photocurrent density. We believe that thin TiO_2 films improve the light response and increase the surface roughness of WO_3 films. Furthermore, the existence of the heterojunction results in the efficient charge carriers' separation, transfer process, and a lower recombination of electron-hole pairs, which is beneficial for the enhancement of photocurrent density.