Abnormal thermal quenching and application for w-LEDs: Double perovskite Ca2InSbO6:Eu3+ red-emitting phosphor

Double perovskite compounds have the advantages of excellent chemical stability. Herein, a series of red-emitting Ca2InSbO6 (CISO):Eu3+ phosphors were synthesized through the high-temperature solid-state method. Phase purity, elemental composition, photoluminescence properties, and luminescence decay were investigated in detail. Under 395 nm excitation, the CISO:0.80Eu3+ phosphor manifested a brilliant red emission peak at 616 nm due to the 5D0→7F2 transition of Eu3+. The optimal doped concentration of Eu3+ was 0.80 mol. The critical distance (Rc = 8.41 A) was calculated. The dominant concentration-quenching mechanism of Eu3+ was ascribed to the electric dipole–dipole interaction. Compared with commercial red phosphors (e.g., Y2O2S:Eu3+, and Y2O3:Eu3+), the Commission International del’Eclairage (CIE) chromaticity coordinates of the CISO:0.80Eu3+ phosphor (0.656, 0.338) were very close to those of the National Television System Committee [(0.670, 0.330)]. Impressively, the CISO:Eu3+ phosphors exhibited abnormal thermal-quenching phenomenon. Up to 380 K, the CISO:0.80Eu3+ phosphor did not exhibit thermal quenching, and its intensity increase was about 14%. The thermal-quenching mechanism was studied in detail, and the thermal activation energy (Ea) was found to be 0.34 eV. The CISO:0.80Eu3+ phosphor also had a high color purity (98.2%). Moreover, the internal quantum efficiency of the CISO:0.80Eu3+ phosphor reached as high as 82%. Thus, a white light-emitting diode (w-LED) with low CCT (4553 K), Ra (88.1), and CIE chromaticity coordinates of (0.345, 0.361) were obtained. All these results demonstrated the potential of the Ca2InSbO6:Eu3+ phosphors as red-emitting substitutes for w-LEDs.