Near-UV and blue wavelength excitable Mg0.6Ca2.16Mo0.2W0.8O6: Eu0.123+/Na0.12+ high efficiency red phosphors

• LED excitable Mg0.6Ca2.16Mo0.2W0.8O6: Eu0.123+/Na0.12+ phosphors were synthesized.
• These phosphors are 10 times more intense than CaMoO4: Eu3+ red phosphors.
• Their intensity and efficiency were enhanced by materials optimization techniques.
• Such techniques include compositional alloying, charge compensation, etc.

Red phosphors with narrow emission around 615 nm (with FWHM~5–10 nm) having chemical compositions of A0.6Ca2.16Mo0.2W0.8O6: Eu0.123+/Na0.12+ (A=Mg, Sr) have been found to exhibit the highest luminescence amongst the molybdate–tungstate family when excited by sources in the 380–420 nm wavelength range. Thus they are most suitable for enhancing color rendering index and lowering color temperature in phosphor converted white LEDs (pc-WLEDs) with near-UV/blue LED excitation sources. The excitation band edge in the near UV/blue wavelength in the reported phosphor has been attributed to the coordination environment of the transition metal ion (Mo6+, W6+) and host crystal structure. Furthermore the quantum efficiency of the phosphors has been enhanced by adjusting activator concentration, suitable compositional alloying using substitutional alkaline earth metal cations and charge compensation mechanisms.

The charge transfer excitation of orthorhombic Mg0.6Ca2.16Mo0.2W0.8O6: Eu0.123+/Na0.12+ is significantly higher than tetragonal CaMoO4: Eu3+ phosphors making Mg0.6Ca2.16Mo0.2W0.8O6: Eu0.123+/Na0.12+ prime candidates for fabrication of warm white phosphor-converted LEDs.Figure optionsDownload as PowerPoint slide