Enhanced long-wavelength transient photoresponsiveness of WO_3 induced by tellurium doping

摘要

Tungsten trioxide (WO_3) films doped with 0.25 atom% tellurium synthesised by a sol-gel route, show strong transient photocurrents under chopped sub-bandgap illumination (hv = 1.8 eV < E_g) at low bias potentials from 0.2 to 0.7 V; such effects are ascribed to the presence of a localized narrow band (NB) between the VB and the CB in this material.rnTungsten trioxide (WO3) thin films have a wide range of applications due to their gas sensing, electrochromic and photocatalytic properties. Such films are also promising electrode materials for the photoelectrochemical oxidation of water to produce hydrogen. However, the energy conversion efficiencies of such films are generally low; mainly because the band gap of crystalline WO_3 is E_g = 2.6 eV which places limits on absorption of solar radiation. In order to modify the band gap. and modify light absorption properties, different elements were doped into WO3 films. It was observed that tellurium-doping induced unique photoelectro-chemical properties.