Ab Initio Calculation and Study of Luminescence Properties of SrTiO3:Pr³+ Materials Codoped with Metal Ions

We have presented and discussed particularly that metal ion dopings influence on the photoluminescent property of SrTiO₃:Pr³⁺ series crystals using the density functional theory (DFT) of Ab Initio, in which Pr impurities substitute for Sr ions in SrTiO₃. The calculations show that Al/Pr ionic codoped model has the stablest structure among the codoped models that SrTiO₃:Pr³⁺ materials are mixed with different metals ions (Li⁺, Mg²⁺ and Al³⁺). The impurities of rare earth and metal ions make the indirect bandgap SrTiO₃ change into direct bandgap, and the bandgap Eg is also narrowed. 2 impurity levels of Pr³⁺ emerge in the middle of the band gap. Further, the number of DOS (density of state) peaks of the models codoped with Pr and metal ion (in which the two kinds of impurities such as Li/Pr, Mg/Pr or Al/Pr ions are added to SrTiO₃ crystalline structure together) is reduced, which shows that some levels have degenerated. Moreover, the d,f electron DOS and O(2p)-Ti(3d) DOS distribution of Pr ion are analyzed, the result shows that DOS in Al³⁺/Pr³⁺ codoped SrTiO₃ model is the most favorable for the red emission. The population analysis indicates that the electrons in the polyhedron are more active than outward, which is constructed with the Pr, O and metal ion and is key structure for red luminescent transitions.