High-efficiency and thermal-stable Ca3La(GaO)3(BO3)4:Eu3+ red phosphors excited by near-UV light for white LEDs

Abstract

The Ca3La(GaO)3(BO3)4:Eu3+ (CLGB:Eu3+) red-emitting phosphors with high-efficiency and splendid thermal stability were prepared by a solid-state method. The synthesized samples were analyzed by X-ray diffraction, photoluminescence spectra, fluorescence decay curves, temperature-dependent photoluminescence spectra, diffuse reflection spectra and internal quantum efficiency. All the CLGB:Eu3+ compounds showed strong red emission peaking at around 621 nm under 397 nm excitation and the best doping concentration was 60 mol%. What's more, CLGB:Eu3+ phosphors also displayed excellent thermal stability and the emission intensity at 423 K maintained 78.6% of original value at 303 K. Furthermore, the internal quantum efficiency of the resultant phosphors reached up to 82.2%. By combining a near-ultraviolet chip, (Ba,Sr)2SiO4:Eu2+ green-emitting phosphors, BaMgAl10O17:Eu2+ blue-emitting phosphors and CLGB:0.6Eu3+ red-emitting phosphors, the fabricated light-emitting diode can generate bright white light with low correlated colour temperature of 3964 K and high colour rendering index of 85. All of these achieved results demonstrate that the CLGB:Eu3+ compounds are potential red-emitting phosphors for the near-ultraviolet chip excited white light-emitting diodes.