First-principles study of persistent luminescence mechanisms in CaB2O4:Ce3+

Abstract First-principles calculations based on the density functional theory (DFT) are carried out to explore the mechanisms of the persistent luminescence (PersL) in CaB2O4:Ce3+ phosphors. Firstly, the energies and Stokes shifts of 4f → 5d transitions of Ce3+ ions in the CaB2O4 are successfully obtained and agree well with the experimental results. Thus, the experimental excitation spectra of the CaB2O4:Ce3+ are assigned successfully. The formation energies and thermodynamic transition levels of candidate intrinsic vacancies (of Ca, O, B and BO), antisite defects (BCa) and Ce3+ ions in the host are calculated in order to understand their effects on the PersL of CaB2O4:Ce3+ phosphors. By combining the presented calculation results and Dorenbos empirical model, the charge transition levels for all the trivalent and divalent lanthanides in the host are derived, which can be adopted to predict the candidate emission and trap centers for the PersL in the lanthanide-doped CaB2O4.