Ab-initio study on opto-electronic properties of non-metal doped TiO2

We have addressed the role of non-metal dopant i.e. Fluorine (F) in bulk TiO2 anatase using first-principles based calculation under the framework of hybrid density functional theory. We have considered two different configurations for the F impurities including: F substituted O (FS) and F as interstitial (Fi). We have obtained from defect formation energy that F has predominant preference for occupying substitutional site with two hole trapped (+2 charge state). In addition, we have adopted GW and BSE approach in order to obtain absorption spectrum. Our results reveal that FS give rise to visible-light absorption in agreement with experimental observations.