Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes

Abstract

We report on the synthesis and photoluminescent performance of the Ba2+ ions doped Eu(HCOO)3 phosphors as well as their promising applications in indoor illumination. The thermal stability of the synthesized sample with microparticles was characterized by the thermogravimetric analysis. Irradiated by 396 nm light, the unique emissions of Eu3+ ions originating from the 5D0 → 7FJ (J = 1, 2, 3, 4) transitions were observed. With the aid of the Judd-Ofelt theory, the local symmetry properties of the Eu3+ ions in the selected host were studied, revealing that the sites taken by the Eu3+ ions possessed low symmetry with non-inversion center. An enhanced luminescent intensity was seen in the resultant phosphors when the Ba2+ ions were introduced and the optimal doping content was 10 mol%. The studied samples can exhibit bright visible red emission with high color purity of 93.3% upon 396 nm excitation. Moreover, the resistance of the emission intensity to the temperature was also explored and the activation energy was 0.188 eV. Furthermore, the internal quantum efficiency of the resultant samples was 67% when excited by 396 nm. Ultimately, a light-emitting diode (LED) lamp, which emitted warm white light with high color rendering index of 80.7 and low color correlated temperature of 4715 K, was constructed, indicating the feasibility of the synthesized phosphors for white-LED.