Ab-initio study of indium, nitrogen codoping effect on the structure and properties of TiO2

Abstract

With indium and nitrogen as a pair of dopants, different substitutional defects are induced in the structure of anatase TiO2. Along with substitutional point defects, oxygen vacancy is created for charge compensation/stabilization of the defect induced system. The In 5p states associated with the indium are coupled with the O 2p states narrowing the band gap of TiO2, and inducing visible light absorption. Nitrogen doping in TiO2 created isolated N 2p stated above the valence band maximum. With respect to the position of dopants, three different In, N co-doped models are introduced. Moreover, the In, N compensated co-doped configuration is also developed. The In 5p and N 2p states of the dopants are strongly coupled with the host O 2p states reducing the band of TiO2. The indium and nitrogen doped 5.477 Å apart from each other in the lattice of TiO2 (anatase) provided maximum absorption in the visible regime among the codoped models. The theoretical findings can explain the experimental observations and widen the applications spectrum of TiO2.