Single White-Emitting Phosphor (Ba,Sr,Ce)_4–mLi(Si,Al)_19+2m(O,N)_29+m for White LEDs

Abstract

A new sialon compound, with the composition (Ba,Ce,Sr) 4−m Li(Si,Al) 19+2m (O,N) 29+m (m = 0.3, n = 1), has been discovered. It crystallizes in the P3m1 space group, with two types of Ba/Sr sites: a ninefold coordinated site located in the cavities of the SiN 4 tetrahedral framework and a sixfold coordinated site that is in substitutional disorder with a (Si/Al) 2 (O,N) group. This interesting structural feature gives rise to a rare occurrence of (Si,Al) atoms in a fivefold trigonal bipyramidal configuration with (O,N) anions, as confirmed by high-resolution solid-state 29 Si MAS NMR and 27 Al 2D 3QMAS NMR spectroscopy. At high Ce concentrations, the Ce ions substitute on both Ba/Sr sites, resulting in white light emission upon UV light excitation due to a double broad-band emission with peaks around 465 and 625 nm. This is a rare occasion of a single activator white-light-emitting phosphor, and the first Ce-doped sialon-based one to be reported. The new phosphor is promising for UV-excitable white LED applications because a single white-light-emitting phosphor with a single dopant does not rely on energy transfer between different activators or a complicated color balance for RGB phosphors, resulting in a cheaper and easier process to fabricate white LEDs.

Cs2MnCl4:Eu2+: A Near-Violet Light-Triggered Single-Component White Light Emitter

“…Single-component white-light-emitting materials exhibit lots of superiorities, such as miniaturizing the equipment, cost reduction, avoiding color drift, and self-absorption. − When fabricated with single-component white light-emitting luminescent materials, phosphor-converted white light-emitting diodes (pc-WLEDs) not only simplify the packaging process (e.g., avoid the huge challenge of balancing the luminescence intensity of multiple components to achieve a uniform distribution of mixed color) but also provide more efficient and stable white light by avoiding the mutual absorption between/among different phosphors . Moreover, single-component white-light-emitting luminescent materials are excited by near-violet light, mitigating the high energy density blue light from the blue LED chip.…”