Ab Initio Investigation on the Effect of Transition Metals Doping and Vacancies in WO₃

We did a density functional theory spin-polarized calculation based on pseudopotential method on the effect of both vacancy and substitutional impurity in the tungsten tri-oxide lattice. We investigated oxygen and tungsten vacancies and for substitutional dopants we used palladium (Pd), platinum (Pt) and gold (Au) atoms with the formula $A_xW_{1-x}O_3$ and x=0.125, 0.25, 0.375, 0.5. We obtained electronic band structure, density of states and magnetization of defected and doped WO₃. The results show that in the presence of tungsten vacancy, WO₃ acts as a semiconductor with an indirect band gap while oxygen vacancy induces a metallic behavior for WO₃. Besides, for Pt and Pd the location of trap states lead to photoexcited hole capturing, which can improve photocurrent but for Au dopant, the trap states occur in the middle of the band gap as active recombination centers. Furthermore, both kind of vacancies and Pt dopant can induce magnetization in all values of x, while Pd and Au are less efficient in inducing magnetization.