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Inorganic Chemistry

New phosphor for LEDs with deep-red-light emission

Cerium-doped nitride compound may lead to applications in horticultural lighting

by Mitch Jacoby
July 20, 2018 | A version of this story appeared in Volume 96, Issue 30


Crystal model of an inorganic phosphor compound.
Credit: Chem. Mater.
The luminescent phosphor depicted here emits deep-red light. Black outline = unit cell. Turquoise tetrahedra = SiN4. Violet tetrahedra = LiN4. Red = O and F. Purple = Li. Orange = La, Ce, or Y.
This is a blue-light-enhanced photo of a phosphor powder.
Credit: Christian Maak/LMU Munich
Shining blue light on this Ce3+-doped phosphor powder causes it to emit deep-red light.

A stroll through the lighting aisle of hardware stores shows that light-emitting diode (LED) products are rapidly surpassing traditional light sources in popularity. Compared with incandescent and some fluorescent lights, LED lamps typically consume less energy, stay cooler, last longer, and are more robust. To tune their output color, manufacturers often modify LEDs with nitride-based luminescent phosphors. Even so, LED lamps still do not emit deep enough into the red portion of the spectrum for some major applications, such as horticultural lighting. A team led by Christian Maak, Philipp Strobel, and Wolfgang Schnick of Ludwig Maximilian University Munich may have come up with a solution. The researchers prepared a family of Ce3+-doped nitridolithosilicates and have shown that they exhibit unprecedented deep-red emission. Related Ce-doped phosphors, which are widely used in LED lighting, emit in the blue to yellow-orange spectral range (Chem. Mater. 2018, DOI: 10.1021/acs.chemmater.8b02604). The team made the compounds via solid-state metathesis chemistry by reacting rare-earth trifluorides, calcium fluoride, silicon nitride, lithium nitride, and the oxides of yttrium, lanthanum and cerium.


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