Persistent Emission of Narrowband Ultraviolet-B Light upon Blue-Light Illumination

Ultraviolet luminescence holds potential for diverse applications. Further development of ultraviolet-luminescence technology, however, is hindered by the common but very inconvenient photoluminescence form. Here we create a form of ultraviolet emission-persistent luminescence in the narrowband ultraviolet-B (NB UVB) region (309--313 nm) upon illumination by a blue light-emitting diode. On this basis, we study the dynamic competition between an up-conversion charging excitation and a photostimulated detrapping upon illumination by the light-emitting diode. Such a competition mechanism, as well as the associated manipulation technique, appears to be generally applicable for many existing phosphors. As a proof of concept, we present an imaging demonstration, showing the potential of the NB-UVB persistent luminescence in the optical tagging field. This work can potentially revolutionize the ways for utilizing persistent luminescence, leading NB-UVB applications to another level.