A broadband near‐infrared Sc1−x(PO3)3:XCr3+ phosphor with enhanced thermal stability and quantum yield by Yb3+ codoping

Abstract

AbstractBroadband near‐infrared (NIR) phosphors converted light‐emitting diodes (pc‐LEDs) have attracted tremendous attention for their great potential in NIR spectroscopy applications. Herein, we report on the photoluminescence (PL) properties of Cr3+‐doped Sc(PO3)3, which exhibits a broadband NIR emission centered at 900 nm with a full width at half‐maximum (FWHM) of 161 nm upon excitation at 480 nm. In terms of the examination of spectroscopic parameters, we find that Cr3+ ions occupy a weak crystal field site (Dq/B = 1.94) in the Sc(PO3)3 host with a stronger electron–phonon coupling (Huang‐Rhys factor, S = 5.5), which results in a serious thermal quenching and a low internal quantum efficiency (IQE). Thermal stability and IQE of phosphors can be substantially enhanced by the introduction of Yb3+ ions. In the light of the analysis of excited‐state dynamics, we demonstrate that the enhancement mechanism is ascribed to the efficient Cr3+→Yb3+ energy transfer from the thermal sensitive Cr3+ centers to the thermal stable Yb3+ emitters. An NIR pc‐LED device has been finally fabricated by the combination of a blue‐emitting chip and a Cr3+/Yb3+ codoped Sc(PO3)3 phosphor whose potential application for broadband NIR pc‐LEDs is also discussed.