A potential red-emitting phosphor Na2.5Zr2Si1.5P1.5O12: Eu3+ for WLEDs with excellent thermal stability, color purity and high quantum efficiency

Abstract

Developing and researching high quantum efficiency red phosphor with small thermal quenching performance was vital for white light-emitting diodes (WLEDs). Herein, a series of novel red emitters Na2.5Zr2-xSi1.5P1.5O12: xEu3+ (NZSPO: Eu3+, 0 ≤ x ≤ 0.07) were prepared and studied. The detailed crystal structure, morphology features and coordinated information of the cations were studied by X-ray diffraction, Rietveld refinement and SEM. The spectral analysis results showed that NZSPO: Eu3+ phosphor could exhibit excellent CIE chromaticity coordinate and high color purity. Excitingly, the internal quantum efficiency of the optimized NZSPO: 0.05Eu3+ could reach 72.14%. And the intensity could still keep 93.3% compared with the initial emission intensity at 140 °C. The concentration quenching mechanism was investigated and then demonstrated to be dominated by the dipole-dipole interaction. In addition, the lifetime of NZSPO: Eu3+ decreased with the increase of Eu3+ concentration, and the average decay time was 1.85 ms. The CCT of the white light emitted by the packaged WLED was 5337 K and the CIE coordinates could reach (0.3357, 0.3338), which was on the verge of the standard white coordinates (0.33, 0.33). All the results showed that NZSPO: Eu3+ could be served as a prospective red light-emitting phosphor for WLEDs.