Divalent europium-doped near-infrared-emitting phosphor for light-emitting diodes

Abstract

Near-infrared luminescent materials exhibit unique photophysical properties that make them crucial components in photonic, optoelectronic and biological applications. As broadband near infrared phosphors activated by transition metal elements are already widely reported, there is a challenge for next-generation materials discovery by introducing rare earth activators with 4 f-5 d transition. Here, we report an unprecedented phosphor K ₃LuSi ₂O ₇:Eu ²⁺ that gives an emission band centered at 740 nm with a full-width at half maximum of 160 nm upon 460 nm blue light excitation. Combined structural and spectral characterizations reveal a selective site occupation of divalent europium in LuO ₆ and K2O ₆ polyhedrons with small coordination numbers, leading to the unexpected near infrared emission. The fabricated phosphor-converted light-emitting diodes have great potential as a non-visible light source. Our work provides the design principle of near infrared emission in divalent europium-doped inorganic solid-state materials and could inspire future studies to further explore near-infrared light-emitting diodes.

Abstract

Here the authors report a near-infrared K ₃LuSi ₂O ₇:Eu ²⁺ phosphor for non-visible light source application. The selective site occupation of Eu ²⁺ in LuO ₆ and K2O ₆ polyhedrons is found to be responsible for the light emission and these insights could serve as design principles for discovery and design of such phosphors.