Extending the applications for lanthanide ions: efficient emitters in short-wave infrared persistent luminescence

Trivalent lanthanide ions (Ln3+) have been extensively used as emitters in short-wave infrared (SWIR; 900–1700 nm) photoluminescence for many advanced applications. Herein, we report that some Ln3+ ions can also act as efficient emitters for SWIR persistent luminescence. Using Ca2SnO4 as a host, we achieved strong SWIR persistent luminescence from a group of six Ln3+ ions, Nd3+, Pr3+, Yb3+, Ho3+, Tm3+ and Er3+, with the emission wavelengths tunable from ∼900 nm to ∼1550 nm. A direct relationship between the depth of electron traps and the ionic radii of Ln3+ ions was obtained. This study greatly expands the field of persistent luminescence in the SWIR spectral region, and the Ln3+ ion-activated Ca2SnO4 SWIR persistent phosphors are expected to have promising applications in a variety of areas such as biomedical imaging and night-vision surveillance.