Multiplexed excitations KGd1−xEux(MoO4)2 red-emitting phosphors with highly Eu3+ doping for white LED application
To research and develop the potential red emission phosphors for warm white-light-emitting diodes (WLED), we systematically investigated double alkaline rare-earth molybdates KGd 1− x Eu x (MoO 4 ) 2 (0.05 ≤ x ≤ 1) phosphors. The crystal structure, morphology, chemical composition, and photoluminescence properties of the phosphors with different Eu 3+ doping concentrations were investigated in detail. The results indicate that Eu 3+ doping concentration can affect the crystal structure and morphology of KGd 1− x Eu x (MoO 4 ) 2 phosphors. The luminescence performance reveals that KGd 1− x Eu x (MoO 4 ) 2 phosphor could emit intense red emission under multiplexed excitations at 362, 382, 394, 465, and 535 nm, which are matched well with the commercial UV, blue and green LED chips. An abnormal quenching behavior was observed in the KGd 1− x Eu x (MoO 4 ) 2 phosphors. And the quenching behavior at the excitation of Eu 3+ –O 2− Charge-Transfer band and Eu 3+ ions 4 f –4 f transitions is quite different. Finally, we fabricated a WLED lamp by coating the InGaN blue chip with a mixture of YAG: Ce 3+ yellow phosphors and KEu(MoO 4 ) 2 red phosphors. The obtained WLED lamps showed warm white light with a lower CCT value (~ 5142 K) than that fabricated without the red phosphors (CCT = 5892 K). These results proved that the KGd 1− x Eu x (MoO 4 ) 2 could be a very promising red-emitting phosphor for WLED.
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