Effect of N impurity on the electronic structure and absorption spectrum of Ba2SiO4:Eu2+ phosphor

The influence of N impurity on the electronic properties and absorption spectra of Ba2SiO4:Eu2+ is studied. It is found that N atoms doping provide many states near the Femi level, which results in narrow band gap and interband transition originating from N2p to the Eu4f. Eu2+ ions experience a strong nephelauxetic effect and crystal field because of the coordinating of N atoms and short coordination distance around the activated centers, which leads to Eu4f and5d states splitting. Therefore, the red-shift of the absorption spectrum in the wavelength of 220-470 nm occurs for the N-doped Ba2SiO4:Eu2+ phosphors.