Experimental and theoretical study on the green persistent luminescence phosphor Ca5Ga6O14:Bi3+

In this study, we developed a type of green persistent luminescence (PersL) material Ca5Ga6O14:Bi3+, which could be excited by UV light ranging from 270 nm to 360 nm with peak at 325 nm and exhibited a broad afterglow band peaking at 515 nm with the duration of about 11 min, which can be ascribed to the electron transitions between the 6s orbital and the 6p orbitals of Bi3+ ion. The thermoluminescence investigation and the First-principle calculation results revealed that the 6s orbital of Bi3+ was about 0.2 eV above the valence band maximum, while the 6p orbitals were 0.6–1.0 eV below the conduction band minimum. Moreover, we found that O vacancies and −2 charged Ga vacancies could form defect levels just above valence band and serve as the hole-trap centers, playing the key role in the process of the afterglow of Ca5Ga6O14:Bi3+. The possible afterglow mechanism was discussed in detail. This work offers an efficient way to construct Bi3+ doped PersL phosphors with desired properties.