Facile synthesis and spectroscopic characterization of siliconitride phosphors for white light-emitting diodes

A modified chemical vapor deposition (CVD) technique is used to synthesize the color-tunable siliconitride Sr2-1.5x-yCexEuySi5N8 (x=0.000-0.016 and y=0.000-0.020) phosphors. In comparison with the conventional solid-state method, the CVD approach successfully improved the crystallinity, particle size distribution, and photoluminescence through the enhanced gas-solid reaction. Under blue excitation, Sr1.98Eu0.02Si5N8 exhibited a red emission band at 618nm. The incorporation of Ce3+ ions increased the emission intensity of Eu2+ ions by approximately 10% owing to the enhanced absorption and dipole-dipole energy transfer process from Ce3+ to Eu2+ ions. It resulted in a shift of the emission colors from yellow to red region. The external and internal quantum efficiencies of Sr1.906Ce0.06Eu0.004Si5N8 were calculated as 54% and 70%, respectively. The activation energy of thermal stability for Sr1.906Ce0.06Eu0.004Si5N8 was evaluated as 0.31eV. A white LED with a color rendering index of 80 and a CCT of 4964K was successfully fabricated with the present phosphors. The current research demonstrated a new series of Sr2Si5N8:Ce3+, Eu2+ phosphors with color-tunability for fabricating white LEDs with high color-rendering index.