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Facile synthesis and spectroscopic characterization of siliconitride phosphors for white light‐emitting diodes
Author(s) -
Lu ChungHsin,
Yang CheYuan,
Som Sudipta,
Das Subrata
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15914
Subject(s) - phosphor , color rendering index , photoluminescence , materials science , analytical chemistry (journal) , light emitting diode , ion , color temperature , crystallinity , emission intensity , luminescence , thermal stability , optoelectronics , chemistry , organic chemistry , chromatography , composite material
A modified chemical vapor deposition (CVD) technique is used to synthesize the color‐tunable siliconitride Sr 2‐1.5x‐y Ce x Eu y Si 5 N 8 (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, Sr 1.98 Eu 0.02 Si 5 N 8 exhibited a red emission band at 618 nm. The incorporation of Ce 3+ ions increased the emission intensity of Eu 2+ ions by approximately 10% owing to the enhanced absorption and dipole‐dipole energy transfer process from Ce 3+ to Eu 2+ ions. It resulted in a shift of the emission colors from yellow to red region. The external and internal quantum efficiencies of Sr 1.906 Ce 0.06 Eu 0.004 Si 5 N 8 were calculated as 54% and 70%, respectively. The activation energy of thermal stability for Sr 1.906 Ce 0.06 Eu 0.004 Si 5 N 8 was evaluated as 0.31 eV. A white LED with a color rendering index of 80 and a CCT of 4964 K was successfully fabricated with the present phosphors. The current research demonstrated a new series of Sr 2 Si 5 N 8 :Ce 3+ , Eu 2+ phosphors with color‐tunability for fabricating white LEDs with high color‐rendering index.