Dy3+/Tm3+ activated single-phase tungstate phosphors with anti-thermal quenching and tunable luminescence properties for white LEDs applications

Phosphor-converted white light emitting diodes (pc-WLEDs) as a new green lighting source have attracted considerable attention around the world. Single-component white light emitters are particularly attractive for fabricating economical solid-state devices for display and lighting. However, the emission loss of phosphors caused by thermal quenching is one of the important factors limiting its application. Herein, a series of single-phase Li3Ba2Y3(WO4)8:Dy3+,Tm3+ phosphors were synthesized by solid state reaction. The crystal structure, electronic structure, morphology, temperature dependent photoluminescence and decay lifetimes were systematically studied by experimental and theoretical calculations. Under the UV excitation, the phosphor could easily emit yellow, blue and white light by simply tuning the ratio of Dy3+ to Tm3+ ions. Notably, the obtained phosphors showed an anti-thermal quenching at 422 K, and the luminous intensity remained 93.09 % of that at room temperature even up to 472 K. Moreover, the CIE chromaticity coordinates hardly changed with the increase of temperature. Ultimately, by combining the phosphor with a 365 nm NUV chip, a high-performance pc-WLED device with a correlation color temperature of 4333 K and CIE coordinates of (0.328,0.396) was successfully realized. This work indicates that the designed single-phase Li3Ba2Y3(WO4)8:Dy3+,Tm3+ may be potential candidates for efficient single-phased white emission in pc-WLED lighting applications.