Luminescent properties of Sr2MgSi2O7:Eu2+ as blue phosphor for NUV light-emitting diodes

Akermanite phosphor Sr2MgSi2O7:Eu2+ was synthesized by solid-state reaction under a H2–N2 atmosphere, and its photo-physical behaviors were systematically characterized by photoluminescence excitation and emission spectra, concentration quenching, and thermal quenching process. This phosphor is efficiently excited in the wavelength range of 300–420 nm, which matches to a near UV-emitting InGaN chip, and emits strong and wide band blue light peaking at 470 nm. The relationship between emission peak wavelength and Eu2+ occupied sites was illuminated through Van Uitert's equation. The concentration quenching mechanism was verified to be a dipole–dipole interaction and the critical energy-transfer distance was confirmed as around 13 Å through both calculated crystal structure method and experimental spectral method. The activation energy for thermal quenching was calculated to be 0.4044 eV. Phosphor-converted LED was fabricated with Sr2MgSi2O7:0.06Eu2+ and 395 nm-emitting InGaN chip and exhibited strong wide band blue emission. These results indicate that Sr2MgSi2O7:Eu2+ is a promising candidate as a blue component for near UV-based multi-phosphor-converted white LEDs.

Graphical AbstractThe graphical abstract shows the emission spectra of Sr2MgSi2O7:Eu2+ under NUV excitation at 395 nm and the excitation spectrum by monitoring blue emission of Sr2MgSi2O7:Eu2+. The inset shows the photo of blue LED prepared by Sr2MgSi2O7:Eu2+ and NUV chip. It indicates that this phosphor can be excited by UV light and emit strong blue light.Figure optionsDownload as PowerPoint slide