Electrical stimulation for brighter persistent luminescence

Abstract

An immature understanding of the mechanisms of persistent luminescence (PersL) has hindered the development of new persistent luminescent materials (PersLMs) with increased brightness. In this regard, in-situ direct current (DC) electric field measurements were conducted on a layered structure composed of the SrAl2O4:Eu2+,Dy3+ phosphor, and an electrode. In this study, the photoluminescence (PL) and afterglow properties were investigated with respect to voltage by analyzing the current signal and thermoluminescence (TL) spectroscopy. The intensity of PersL increased due to a novel phenomenon known as “external electric field stimulated enhancement of initial brightness of afterglow”. This dynamic process was illustrated via the use of a rate equation approach, where the electrons trapped by the ultra-shallow trap at 0.022 eV could be transferred through the conduction band during long afterglow. The afterglow intensity could reach 0.538 cd m−2 at a 6 V electric voltage. The design of an electric field stimulation technique enables the enhancement of the intensity of PersLMs and provides a new perspective for exploring the fundamental mechanics of certain established PersLMs.