Drastic enhancement of blue-to-orange color conversion efficiency in heavily-doped ZnS:Mn2+ phosphor and its application in white LEDs

Autor: J.S. Kim, G. Deressa, Taewook Kang, Kye-Hun Park
Rok vydání: 2018
Předmět:
Zdroj: Journal of Luminescence. 194:551-556
ISSN: 0022-2313
DOI: 10.1016/j.jlumin.2017.07.036
Popis: Heavily-doped ZnS:Mn 2+ phosphors showed an extremely enhanced photoluminescence excitation intensity at 464 nm peak wavelength originated from 6 A 1 ( 6 S)→ 4 A 1 ( 4 G) forbidden transition of Mn 2+ ions. The best ZnS: Mn 2+ phosphors showed the intensive orange color emission of 584 nm peak wavelength from 4 T 1 ( 4 G) → 6 A 1 ( 6 S) forbidden transitions with an excellent lumen maintenance of 97% at 200 °C, and their quantum efficiency of 75% under the 464 nm excitation wavelength. The photoluminescence enhancement was explained in terms of the relaxation of selection rule on the forbidden intra-transitions of Mn 2+ ion. It was caused by the spin-spin and the electron-phonon interactions supported by electron spin resonance signal and Raman spectroscopy, respectively. The excellent lumen maintenance was explained in terms of resonance-assistant direct intra-transition caused by the coupling between an excited electron (e*) on the 4 A 1 ( 4 G) state and multi-phonon energy. To evaluate its feasibility for white light-emitting diodes, the optimized ZnS:Mn 2+ phosphor and its mixture with a green Lu 3 Al 5 O 12 :Ce 3+ phosphor were applied to a 460 nm blue-light-emitting diode. It showed high luminous efficiency of 68 lm/W, suggesting a possibility on the application of Mn-doped ZnS phosphor for pc-WLED.
Databáze: OpenAIRE
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