N-N双掺锐钛矿相二氧化钛电子结构及光学性质的第一性原理研究

First-principles calculations have been conducted to investigated the electronic structures and optical properties of N-N codoped anatase TiO2 with nine different relative locations. Among these nine codoped systems, there were seven codoped configurations with ferromagnetic couplings between two N atoms. However, antiferromagnetic couplings existed in one of the rest configurations and the other one is a competition between ferromagnetic couplings and antiferromagnetic couplings. The configuration with the farthest distance of two N atoms was found to be the most stable structure. The band structures and density of states showed that several impurity bands had been induced in the band gap region, which can explain the red shift in the fundamental absorption edge of anatase TiO2. The impurity bands were thought to act as the mediums for electron transition from the valence band maximum (VBM) to the conduction band minimum (CBM), providing more chance for carrier mobility.