Tunable cool to warm white emission in Ca 1-x La 2x/3 TiO 3 coped with Dy 3+ and Sm 3+ for white LED application

The luminescence properties of Ca 1-x La 2x/3 TiO 3 :Dy 3+, Sm 3+ phosphors were investigated in this paper. They were characterized by their photoluminescence, thermal quenching, and electroluminescence. At an excitation wavelength of 388 nm, the photoluminescence spectra of the Ca 1-x La 2x/3 TiO 3 :Dy 3+ phosphors exhibited two emission peaks at 482 and 573 nm which were attributed to 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+, respectively. Orange-red Ca 1-x La 2x/3 TiO 3 :Sm 3+ phosphors had three emission peaks at 565, 601 and 648 nm at an excitation wavelength of 404 nm due to the 4 G 5/2 → 6 H J/2 ( J = 5, 7 and 9) transitions of Sm 3+. When Dy 3+ and Sm 3+ were co-doped into Ca 1-x La 2x/3 TiO 3, the phosphors achieved conversion of cool white and warm white light by varying the concentrations of Dy 3+ and Sm 3+. The temperature-dependent emission spectra indicated that the Ca 1-x La 2x/3 TiO 3 :Dy 3+, Sm 3+ phosphors exhibited good thermal stability. White light-emitting diodes (WLEDs) demonstrated that the fabricated Ca 0.7 La 0.2 TiO 3 :Dy 3+, Sm 3+ phosphors had correlated color temperature (CCT) and color rendering index (R a ) values of 6064 K and 71, respectively. They had better performances than commercial WLEDs with a combination of blue LEDs coated with yellow emitting Y 3 Al 5 O 12 :Ce 3+ phosphors (CCT =7760 K, and R a < 65). This study demonstrates that Ca 1-x La 2x/3 TiO 3 :Dy 3+, Sm 3+ phosphors can be promising candidates for NUV chip-based WLEDs.