Extra-Broad Band Orange-Emitting Ce³⁺-Doped Y₃Si₅N₉O Phosphor for Solid-State Lighting: Electronic, Crystal Structures and Luminescence Properties

Abstract

Luminescent materials play an important role in making solid state white light-emitting diodes (w-LEDs) more affordable home lighting applications. To realize the next generation of solid-state w-LEDs with high color-rendering index (CRI), the discovery of broad band and long emission wavelength luminescent materials is an urgent mission. Regarding this, the oxonitridosilicate Y 3 Si 5 N 9 O with a high nitrogen concentration should be a suitable host material to achieve those promising luminescent properties. In this work, a phase-pure Ce 3+ -doped Y 3 Si 5 N 9 O was successfully synthesized through the carbothermal reduction and nitridation method. Y 3 Si 5 N 9 O:Ce 3+ shows an emission maximum at 620 nm and an extremely broad emission band with a full-width at half maximum (FWHM) of 178 nm. The electronic and crystal structure calculations indicate an indirect band gap of 2.6 eV (experimental value: 4.0 eV), and identify two Ce 3+ sites with different local environments that determine the luminescence properties. The orange-emitting phosphor has the absorption, internal and external quantum efficiencies of 89.5, 17.2 and 15.6% under 450 nm excitation, respectively. The valence state of Ce, cathodoluminescence, decay time, and thermal quenching of the phosphor were also investigated to understand the structure-property relationships.

Emitting-tunable Eu(2+/3+)-doped Ca(8−x)La(2+x) (PO4)6−x(SiO4)xO2 apatite phosphor for n-UV WLEDs with high-color-rendering

“…When monitoring with the maximum emission at 613 nm ( 5 D 0 -7 F 2 ), the PLE spectra of x ¼ 3-6 samples mainly consist of a O 2p / Eu 4f charge transfer band (CTB) in 250-335 nm and several 4f-4f transition lines from 350 nm to 500 nm. 19 Especially, the excitation intensities of 7 F 0 -5 L 6 (395 nm) and 7 F 0 -5 D 2 (463 nm) transitions are almost equivalent to or even surpass the O 2p / Eu 4f CTB absorption intensity, revealing that these samples could be effectively excited by 395 nm n-UV and 463 nm blue light. In general, the transformation of Eu 2+ to Eu 3+ happens with the substitution of [Ca 2+ -P 5+ ] for [La 3+ -Si 4+ ] in the CLSPO-x host, in which the Eu 2+/3+ can coexist and be controllably adjusted at appropriate x value.…”

“…Especially, more red component should be covered for presenting high CRI white light. 19 Eu 3+activated materials are potential red-emitting phosphors in pc-WLEDs due to the typical 4f-4f transitions ( 5 D 0,1 -7 F J , J ¼ 0-6) in the range of 570-700 nm from Eu 3+ . [20][21][22] Moreover, cation substitution has been conrmed as an effective strategy to adjust luminescent colors and properties of phosphor materials.…”

Further Representatives of the Type RE3[Si5N9O] (RE = Dy–Er, Yb)

“…In 2001, Thompson et al published a rare earth oxonitridosilicate with the composition Y 3 [Si 5 N 9 O], containing a tetrahedral network of corner‐sharing SiN 4 and SiN 3 O tetrahedra (N [2] , N [3] , and O [1] ) . In 2016, Xie et al discovered extra‐broad orange emission on Ce 3+ ‐doped samples of Y 3 [Si 5 N 9 O] …”

Cooperative cation substitution facilitated construction of garnet oxynitride MgY2Al3Si2O11N:Ce3+ for white LEDs

“…However, the luminescence efficiency decreases with the red shift of Ce 3+ emission as a result of the cation substitution strategy. Fortunately, (oxy)nitride compounds are reported to possess higher efficiency and thermal stability, because the high covalency of N anion will result in a rigid host lattice . Therefore, we intend to construct garnet oxynitride by incorporating N into the garnet host, for the purpose of improving thermal stability and quantum efficiency, along with the redshift of emission.…”