Near‐ultraviolet light–induced dazzling red emission in CaGd₂(MoO₄)₄:2xSm³⁺ compounds for phosphor‐converted WLEDs

Abstract

The Sm3+‐activated CaGd2(MoO4)4 phosphors were prepared through a sol‐gel reaction route. From the results of excitation spectrum, three‐dimensional emission spectra and contour lines, it was confirmed that the near‐ultraviolet (NUV) light was the proper excitation light source for the synthesized phosphors. Under 405 nm irradiation, the luminescent behaviors of the studied samples were revealed to be dependent on the Sm3+ ion concentration and its optimal value of 0.03 mol was obtained. Through theoretical analysis, it is evident that the dipole‐dipole interaction can be responsible for the involved concentration quenching mechanism in the final products and the critical distance was 39.7 Å. Moreover, the temperature‐dependent emission spectra demonstrated that the studied samples had admirable thermal stability and the activation energy was decided to be 0.21 eV. Furthermore, the internal quantum efficiency of the Sm3+‐activated CaGd2(MoO4)4 phosphors was found to be 21.6%. Finally, to explore the practical applications of obtained compounds for indoor illumination, a white light‐emitting diode (WLED) device which contained a NUV chip, prepared phosphors, and commercial blue‐emitting and green‐emitting phosphors was packaged. The packaged WLEDs device can emit dazzling white light with satisfied color coordinate of (0.305, 0.318), proper color rendering index (82.6), and correlated color temperature (7069 K).

Charge compensation engineering for high-performance dolomite-type BaTi(BO3)2:Eu3+ red-emitting phosphor for backlight display applications with a wide color gamut

“…Generally, the concentration quenching effect will reduce the lifetime, [35][36][37] but here, the average lifetime does not show a monotonic downward trend with the increase in the Eu 3+ ion content but reverses when the Eu 3+ ion doping content x ≥ 0.05. This may be because the Eu 3+ ions will spontaneously replace a small amount of Ti 4+ ions at a higher content of Eu 3+ ions, so as to increase the distance between adjacent Eu 3+ ions and effectively alleviate the non-radiative energy transfer between the Eu 3+ ions.…”