Facile synthesis of bifunctional Eu3+-activated NaBiF4 red-emitting nanoparticles for simultaneous white light-emitting diodes and field emission displays

A series of novel Eu3+-activated NaBiF4 nanoparticles were synthesized by an ultra-fast chemical precipitate method at room temperature. Under the excitation of 394 nm, all the compounds emitted glaring red emissions originating from the intra-4f transitions of Eu3+ ions. The optimal doping concentration was found to be 40 mol % and the concentration quenching mechanism was dominated by dipole-dipole interaction. The temperature-dependent photoluminescence emission spectra revealed that the resultant nanoparticles possessed admirable thermal stability with an activation energy of 0.237 eV. The internal quantum efficiency of the synthesized nanoparticles was estimated to be as high as 73.1%. Furthermore, the optical transition parameters of Eu3+ ions were calculated using a facile method based on the Judd-Ofelt theory to explore the local structure environment around the Eu3+ ions in the NaBiF4 host lattice. Additionally, the packaged light-emitting diode (LED) device, which was composed of a near-ultraviolet LED chip, synthesized nanoparticles and commercial blue-emitting/green-emitting phosphors, exhibited brightly white light with high color rendering index of 88.2 and proper correlated color temperature of 6851 K. Ultimately, the studied nanoparticles also had splendid cathodoluminescence properties. These results suggest that the Eu3+-activated NaBiF4 nanoparticles were promising bifunctional materials for simultaneous white LEDs and field emission displays.