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)

In the Editor's Choice [1] 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 doped with Eu2+. These novel LEDs are superior to both incandescent and fluorescent lamps and may therefore become the next generation of general lighting sources. The cover picture is an artist's view of the 2‐pc‐LED: On a copper slug and underneath a plastic lens a ‘flip‐chip’ is soldered to metal contacts; ‘flip‐chip’ meaning the substrate on which the stack of GaN and InGaN layers has been deposited is used as light exit, the (bottom) p‐contacts being highly reflective. The color converting phosphors are placed on top of the chip, embedded in silicone. Primary blue as well as color‐converted red and green photons are emitted. The first author, Regina Mueller‐Mach, manages the Charac‐terization Laboratory at Lumileds which runs R&D work on phosphor converted LEDs in close cooperation with Philips Research Laboratories and the Department of Chemistry and Biochemistry of the University of Munich.

Optical and structural properties of rare earth complexes with 2-pyridine carboxylic acid (' Hpic ') are evaluated by luminescence spectroscopy, decay measurements, X-ray crystal structure determination, FTIR, DTA and metal content analysis. Corresponding Tb 3+ and Eu 3+ complexes of this ligand are extraordinarily efficient with respect to their luminescence. In the crystalline state the series is isostructural and composed of M[Ln(pic) 4 ]ÁnH 2 O (M ¼ Na, NH 4 ; Ln ¼ Eu, Gd, Tb, Ho) with pic-linked [Ln(pic) 4 ] À units forming a chainlike structure, which gives rise to a one-dimensional exchange communication between the rare earth ions; this energy transfer being confined to the chains. Energy transfer of the Coulomb type between the ligands appears to be of significance only, if suitable rare earth acceptor states are not accessible, as is shown for a series of [La(pic) 4 ] À series, in which La 3+ is gradually substituted by Tb 3+ or Eu 3+ .

No abstract

Ion-induced secondary electron emission coefficients for Ne, Ar, and Xe discharges are reproducibly determined using V-Q Lissajous figures. The comparison of measured and calculated Paschen curves results in ion-induced γ-coefficients for glass, MgO, CVD diamond, and phosphors. The measured γ-values correlate well with a simple model based on the ionization energy of the gas ion and the band gap and electron affinity of the solid.

X-ray excitation of LaPO4:Gd3+ nanocrystals results in single-line UV emission capable of activating organic molecules and enabling new biomedical applications.

The performance of two 4-in. color PDP test panels with a default and a high-Xe-concentration gas mixture will be discussed. The default panel with a gas mixture of 3.5% Xe in Ne and a filling pressure of 665 hPa was compared with a panel containing a gas mixture of 13.5% Xe in Ne and a filling pressure of 800 hPa. The panels contain a green phosphor, YBO 3 :Tb, which showed less saturation at high UV load compared with a Willemite phosphor. The panel performance was compared in addressed conditions. For the default panel, a white luminance of 710 cd/m 2 and an efficacy of 1.6 lm/W was found, while for the high-Xe-partial-pressure panel, a white luminance of 2010 cd/m 2 and an efficacy of 3.8 lm/W was realized. The increase of the driving voltages, about 20-30 V, is moderate. Finally, color saturation is improved at high Xe partial pressure.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.