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 4f-5d transition. Here, we report an unprecedented phosphor K3LuSi2O7:Eu2+ 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 LuO6 and K2O6 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.

Pyrophosphate Phosphor Solid Solution with High Quantum Efficiency and Thermal Stability for Efficient LED Lighting

“…In addition, there are three shoulder peaks located at 566, 526, and 491 cm À1 , corresponding to the three different deformations of dOPO, dPO 3 , and dPOP, respectively. The other peaks below 400 cm À1 should be caused by external vibrational modes (Edhokkar et al, 2012;Seyyido glu et al, 2007). By increasing the Ba content in SB x PE (x = 0-0.5) solid solution, we can observe that the peak intensities of PO 3 and POP increased as well.…”

Solid‐State Thin‐Film Broadband Short‐Wave Infrared Light Emitters

“…Cost‐effective phosphor‐based NIR downconverting light emitters known as phosphor‐converted light‐emitting diodes (pc‐LEDs) have been proposed to reduce the size of the light source. [ 11–14 ] The luminescence centers of the so‐far reported phosphor‐based glasses rely on transition metal or rare earth elements mainly utilizing Cr 3+ , Mn 2+ or mixed Yb 3+ /Cr 3+ luminescence centers, [ 15–19 ] developed to address the NIR spectrum. The fundamental challenges in electronic level modification for optical transitions in the SWIR and low stability have hindered the development of SWIR emitting pc‐LEDs with broadband and highly efficient emission.…”

Insights into the complexity of the excited states of Eu-doped luminescent materials

“…For more modern applications, based on white lightemitting diodes (LEDs), Eu 2+ gets into the picture thanks to its low-lying 4f 6 5d 1 configuration, enabling efficient, while yet spectrally relatively narrow emission across the visible and near-infrared spectral range upon excitation with blue or near-UV light 1,[5][6][7][8][9] . The energy difference between the 4f 7 and 4f 6 5d 1 configurations is highly dependent on the chemical envi-ronment of the Eu 2+ ion.…”