Near-infrared luminescence from double-perovskite Sr3Sn2O7:Nd3+: A new class of probe for in vivo imaging in the second optical window of biological tissue

Abstract

Inorganic phosphors that emit near-infrared (NIR) light are highly valued as fluorescent probes for in vivo imaging of biological tissue. NIR-imaging, however, is limited by the paucity of probes that emit over the NIR-II window (1000-1400nm). We are interested in exploring the potential of double-layered perovskite structures harboring lanthanide ions as NIR-II fluorescent probes. In this report, we describe the synthesis, and characterization of the photoluminescence, afterglow and thermoluminescence of Nd3+-doped Sr3Sn2O7 together with an analysis of its structural properties. Sr3Sn2O7:Nd3+ has a double-layered perovskite structure with oxygen octahedral tilt and rotation, which leads to an intense NIR-II luminescence from 4f-4f transition in Nd3+ ions; the intensity of NIR-II photoluminescence of Sr3Sn2O7:Nd3+ is 102 times higher than that of an ordinary perovskite structure, namely SrSnO3:Nd3+. Moreover, we show the intra-layer planar defect in Sr3Sn2O7:Nd3+ contributes to the long-lived NIR-II afterglow. Finally, we show time-resolved imaging of the long-lived NIR-II fluorescence of Sr3Sn2O7:Nd3+ generate highcontrast images of probes embedded within a model tissue.