title: Energy transfer in Sr2MgSi2O7:Eu2+ phosphors in nano scale and their application to solid state lighting with excellent color rendering.
abstract: On the basis of structural information of its host material which shows excellent stability and absorption efficiency in ultra-violet (UV) region, a blue-emitting Sr2MgSi2O7:Eu2+ (SMS:Eu2+) phosphor was synthesized, and its photoluminescence (PL) performance was systematically optimized. In order to enhance its PL properties, Ce3+ was added as a sensitizer based on the energy transfer from the absorption energy of Ce3+ to Eu2+. It was due to the spectral overlap between the photoluminescence excitation spectrum of Ce3+ and the PL spectrum of Eu2+. Moreover, the energy transfer rate from Ce3+ to Eu2+ is generally faster than the emission rate of Ce3+ in the dipole-dipole interaction. Depending upon the amount of Ca2+ substituted into Sr site, their maximum wavelength was varied from -460 to -540 nm in terms of the crystal field effect confirmed by the structural analysis via Rietveld refinement method. Finally, the optimized blue-emitting SMS:Eu2+ and Ca(2+)-substituted yellowish green-emitting SMS:Eu2+ phosphors were applied with Eu(2+)-sensitized red-emitting Ca3Mg3(PO4)4:Mn2+ phosphor introduced in our previous research to UV light emitting diode (LED)-pumped white LEDs. The fabricated white LEDs showed a natural white light with the color coordinate of (0.3298, 0.3280) and the excellent color rendering index of 94.
authors.affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors.forename: Ki Hyuk
authors.initials: KH
authors.lastname: Kwon
authors.forename: Won Bin
authors.initials: WB
authors.lastname: Im
authors.forename: Duk Young
authors.initials: DY
authors.lastname: Jeon