The development and demonstration of a highly efficient warm‐white all‐nitride phosphor‐converted light emitting diode (pc‐LED) is presented utilizing a GaN based quantum well blue LED and two novel nitrogen containing luminescent materials, both of which are doped with Eu2+. For color conversion of the primary blue the nitridosilicates M2Si5N8 (orange‐red) and MSi2O2N2 (yellow‐green), with M = alkaline earth, were employed, thus achieving a high luminous efficiency (25 lumen/W at 1 W input), excellent color quality (correlated color temperature CCT = 3200 K, general color rendering index Ra > 90) and the highest proven color stability of any pc‐LED obtained so far. Thus, these novel all‐nitride LEDs are superior to both incandescent and fluorescent lamps and may therefore become the next generation of general lighting sources. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The new nitridoalumosilicate phosphor SrAlSi 4 N 7 :Eu 2+ has been synthesized under nitrogen atmosphere at temperatures up to 1630 °C in a radio-frequency furnace starting from Sr metal, R-Si 3 N 4 , AlN, and additional Eu metal. The crystal structure of the host compound SrAlSi 4 N 7 has been solved and refined on the basis of single-crystal and powder X-ray diffraction data. In the solid, there is a network structure of corner-sharing SiN 4 tetrahedra incorporating infinite chains of all edge-sharing AlN 4 tetrahedra running along [001] (SrAlSi 4 N 7 : Pna2 1 (No. 33), Z ) 8, a ) 11.742(2) Å, b ) 21.391(4) Å, c ) 4.966(1) Å, V ) 12.472(4) Å 3 , 2739 reflections, 236 refined parameters, R1 ) 0.0366). The Eu 2+ -doped compound SrAlSi 4 N 7 :Eu 2+ shows typical broadband emission originating from dipole-allowed 4f 6 ( 7 F J )5d 1 f 4f 7 ( 8 S 7/2 ) transitions in the orange-red spectral region (λ max ) 632 nm for 2% Eu doping level, 450 nm excitation) with a spectral width of FWHM ) 2955 (( 75) cm -1 and a Stokes shift ∆S ) 4823 (( 100) cm -1 . The luminescence properties make the phosphor an attractive candidate material as red component in trichromatic warm white light LEDs with excellent color rendition properties.

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