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Blue, green, and yellow phosphors are obtained in the Sr1−xY0.98+xCe0.02Si4N7−xCx system (x=0→1). Decreases in thermal quenching barrier height with x result from a dominant neighboring‐cation effect, through which the replacement of Sr2+ by Y3+ reduces the covalency of CeN bonding. Green emission is observed from a cation‐segregated nanostructure of SrYSi4N7 and Y2Si4N6C domains in x=0.2–0.6 samples. [ABSTRACT FROM AUTHOR]

The authors report here the enhanced luminescence properties of SrSi2O2N2 doped with Eu and M (M=Ce, Dy, and Mn). The Eu and Eu, Mn-codoped powders were prepared by a solid state reaction at temperatures between 1400 and 1600 °C under H2 (25%)–N2 (75%) atmosphere. The Eu, M-codoped Sr1-x-ySi2N2O2 phosphors have the monoclinic structure with lattice parameters a∼15.6 Å, b∼16.2 Å, c∼9.4 Å, and β∼91°. The phosphors can be efficiently excited in the UV to visible region, making them attractive as conversion phosphors for a light emitting diode application. A green-yellow emission was observed for Eu,M-codoped Sr1-x-ySi2N2O2. The addition of M in the Eu site in SrSi2O2N2 remarkably enhances the luminescent intensity by the factor of 144%, 148%, and 168% for Ce, Dy, and Mn, respectively. [ABSTRACT FROM AUTHOR]

A novel blue phosphor based on phosphate host matrix, KSrPO4 doped with Eu2+, was prepared by solid state reaction. The phosphor invariably emits blue luminescence with a peak wavelength at 424 nm under ultraviolet excitation at 360 nm. Eu2+-doped KSrPO4 phosphors show higher thermally stable luminescence which was found to be better than commercially available Y3Al5O12:Ce3+ phosphor at temperature higher than 225 °C. [ABSTRACT FROM AUTHOR]

A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 455 nm blue light, and green phosphor SrSi2O2N2:Eu and red phosphor CaSiN2:Ce that emit 538 nm green and 642 nm red emissions, respectively, when excited by the 455 nm blue light. The luminous efficacy of this white LED is about 30 lm/W at a dc of 20 mA. With increasing dc from 5.0 to 60 mA, both the coordinates x and y of the white LED tend to be the same, and consequently the Tc is the same and the Ra increases to 92.2. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) phosphors are enticing photoluminescent materials with applications in light-emitting diodes for spectroscopy. These phosphors have two types of emissions: Type I has a Gaussian curve, whereas Type II is similar to a plateau. Both emissions have industrial uses, but uncertain remains regarding which type is ideal. In this review, we compare two distinct NIR phosphors with Type I and Type II emissions in terms of their structure, crystal field, and emission profile and then provide our perspective on what the ideal emission must be. Image 1 • Near-infrared phosphors as main components for light-emitting diode devices. • Type-I near-infrared emission has a Gaussian curve with high luminescent intensity. • Type-II near-infrared emission has a plateau shape with superior broadband coverage. • Strategy in order to achieve the ideal emission for near-infrared light-emitting diodes. [ABSTRACT FROM AUTHOR]