Luminescence properties and energy transfer behavior of single-component NaY(WO4)2:Tm3+/Dy3+/Eu3+ phosphors for ultraviolet-excited white light-emitting diodes

• Under 358 nm excitation, the obtained samples exhibited the emissions of Tm3+, Dy3+ and Eu3+ ions.
• Owing to the ET from Tm3+ to Dy3+ ions, the emission color of the phosphors was changed from blue to white.
• The ET efficiency in the NaY(WO4)2:0.01Tm3+/xDy3+ phosphors was up to 46.1% when x = 0.05.
• Through theoretical analysis, the ET mechanism from Tm3+ to Dy3+ ions was the dipole–dipole interaction.
• With the tridoping of Eu3+ ions, the CCT value of the as-prepared phosphors was modified.

The single-component NaY(WO4)2:Tm3+/Dy3+/Eu3+ color-controllable phosphors were synthesized by a facile high-temperature solid-state reaction technique. The X-ray diffraction patterns, field-emission electron scanning microscope images and photoluminescence (PL) spectra were measured to characterize the prepared phosphors. All the samples possessed pure tetragonal phase and consisted of micro-sized particles. Under ultraviolet light excitation, the characteristic emissions of Tm3+, Dy3+ and Eu3+ ions were observed. Moreover, the emission color of the NaY(WO4)2:0.01Tm3+/xDy3+ phosphors was tuned from blue to white by adjusting the Dy3+ ion concentration. The PL spectra revealed that there existed an efficient energy transfer (ET) from Tm3+ to Dy3+ ions and the ET mechanism was determined to be a resonant type via dipole–dipole interaction. Through theoretical calculation, the ET efficiency was found to be as high as 46.1% when x = 0.05 and the critical distance was 6.54 Å. With the introduction of Eu3+ ions, the corrected color temperature of the products was modified and the emission color was also changed from pure white to reddish white. These obtained single-component white light-emitting NaY(WO4)2:Tm3+/Dy3+/Eu3+ phosphors were expected to be a potential candidate for phosphor-converted white light-emitting diode applications.

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