Enhancement of Near-Infrared Phosphor Luminescence Properties via Construction of Stable and Compact Energy Transfer Paths

摘要

The rapid development of near-infrared (NIR) spectroscopy urgently requiresthe exploration of NIR-emitting phosphors with excellent luminescenceproperties. Herein, GaTaO_4:Cr~(3+),Yb~(3+) NIR phosphor with excellent luminescenceproperties is reported, which exhibits ultra-broadband NIR emissionwith a full width at half maximum of 300 nm, good thermal stabilityof 90@423 K, and most remarkably, high internal quantum efficiency of95.5 and external quantum efficiency of 44.79. Such outstanding luminescenceproperties mainly give the credit to the unique sandwiched structureof GaTaO_4:Cr~(3+),Yb~(3+), in which layers of Yb~(3+) ions (activator) are sandwichedbetween layers of Cr~(3+) ions (sensitizer), and hence many stable and compactCr–Yb pairs are formed, so that the energy can be rapidly transferred fromCr~(3+) to Yb~(3+), effectively activating the characteristic f–f transition of Yb~(3+) thatis very stable and almost independent of the temperature, and at the sametime, the non-radiative transition of Cr~(3+) ions can be suppressed to a certaindegree. The NIR phosphor-converted light-emitting diodes (pc-LEDs) are fabricatedby combining GaTaO_4:Cr~(3+),Yb~(3+) with blue LED chips, and the applicationpotential is fully demonstrated by non-destructive food detection, nightvision, and vein display. The results provide novel prospects for the design ofNIR-emitting materials with desirable luminescent properties.