UV or blue light excited red persistent perovskite phosphor with millisecond lifetime for use in AC-LEDs

Energy storage phosphors with millisecond period afterglow that compensate for the diming time of alternating current light-emitting diodes (AC-LEDs) have promising application. To obtain a persistent luminescence (PersL) white colour in AC-LEDs, we focussed on a red afterglow with short period phosphorescence. Ca4Ti3O10 forms a type of perovskite-related Ruddlesden-Popper phase structure. Doping Pr3+ ions into Ca4Ti3O10, an ideal red PersL was obtained. X-ray diffraction and element analysis demonstrated that our target samples were crystallized well. Steady-state and afterglow luminescence properties were investigated in detail. Notably, the PersL intensity was dependent on various excitation wavelengths. By measuring three-dimensional thermoluminescence spectra, we found that the trap depths showed a continuous distribution and that the shallowest trap contributed to the millisecond afterglow. Two PersL mechanism models were used to elucidate the electron charging and de-trapping processes under UV or blue light activation.