Luminescence properties of stoichiometric EuM₂S₄ (M = Ga, Al) conversion phosphors for white LED applications

Abstract

EuM2S4 (M = Ga, Al) phosphors were synthesized using the solid‐state reaction method. The structure and photoluminescence (PL) properties of the phosphors were investigated in detail. XRD pattern results indicated that the two phosphors are isostructures to the orthorhombic structure. The PL spectra showed that the EuGa2S4 and EuAl2S4 phosphors can be excited efficiently by UV–visible light from 350 to 480 nm and that they emit intense green and bluish‐green light, with emission bands peaking at 545 and 506 nm, respectively. The fluorescence lifetimes of Eu2+ were calculated to be 0.076 and 0.064 µs for EuGa2S4 and EuAl2S4, respectively. The thermal quenching temperature was 412 K for EuGa2S4. A green LED was fabricated by the combination of a near‐UV InGaN chip and the prepared EuGa2S4 phosphor. The EuGa2S4 phosphor exhibits much better green color purity than EuAl2S4. As a result, EuGa2S4 might be a promising green phosphor candidate for solid‐state lighting LED technology.

Blue emission of Eu2+-doped translucent alumina

“…The emission intensity weakly decreases as the temperature raising up to about 100 K followed by a faster decrease observed in the range 150-300 K, representing the different nonradioactive processes during these two temperature region. The process could be described by the following Arrhenius equation [46][47][48] I T I…”

Highly Luminescent Multicomponent Green Phosphor for a White Light‐emitting Diode

“…Thiogallate‐based luminescent materials doped with Eu 2+ have attracted great interest for light‐emitting diode (LED) applications . Phosphors of MGa 2 S 4 :Eu 2+ (M = Sr and Zn) excited with blue light produce green luminescence.…”

Photoluminescence Characteristics of a New Thiogallate‐Based Green‐Emitting Phosphor: MgGa2S4:Eu2+

“…SrGa 2 S 4 :Eu 2+ also shows a very high green emission and can be efficiently excited by blue‐emitting diodes . SrGa 2 S 4 :Ce 3+ , Pb 2+ , ZnGa 2 S 4 :Eu 2+ , and EuGa 2 S 4 phosphors have also been studied as possible phosphors for white LEDs . The structural and luminescence properties of Ca 1− x Sr x (Ga 1− y Al y ) 2 S 4 :Eu 2+ phosphors have been described by Yu et al .…”

“…The MgGa 2 S 4 –MgSc 2 S 4 samples were prepared using Mg, S, and the binary sulfides Ga 2 S 3 and Sc 2 S 3 in evacuated silica glass ampoules in a process with a duration of 14 d. From this discussion, we find that the sealed vacuum quartz‐tube synthesis is highly complex and not convenient to use in the large‐scale preparation of polycrystalline MgGa 2 S 4 :Eu phosphors. In the conventional solid‐state synthesis of MGa 2 S 4 :Eu 2+ (M = Ca, Sr, Ba, Zn) phosphors, a H 2 S atmosphere is always used to carry out the sulfurization reaction between the metal oxides and the carbonates . However, this technique is unsuitable for the preparation of MgGa 2 S 4 :Eu because of the higher stability of magnesium carbonate basic MgCO 3 ·4Mg(OH) 2 ·5H 2 O.…”