Excitation wavelength and Eu3+/Tb3+ content ratio dependent tunable photoluminescence from NaSrBO3:Eu3+/Tb3+ phosphor

A series of single doped (Eu3+ or Tb3+) and codoped (Eu3+ and Tb3+) phosphors were synthesized by solution combustion method. The single doped NaSrBO3:Tb3+ and NaSrBO3:Eu3+ emit green and red emission due to the characteristic 4f–4f transition of the Tb3+ and Eu3+ ions, respectively, under respective excitation wavelengths. Whereas, under Tb3+ excitation, the co-doped NaSrBO3:Tb3+/Eu3+ phosphors showed tunable emission upon varying the Eu3+/Tb3+ content ratio ascribed due to the energy transfer from Tb3+ to Eu3+ ions. Instead of this the emission spectrum of the codoped phosphors also exhibited strong dependence on the excitation wavelength in the range from 240 to 394 nm. The shift in the emission color (green–yellow–red) with increasing excitation wavelength, had been attributed to the presence of multiple states of Eu3+ and Tb3+ ions in the material, that become active at different excitation wavelength. The energy transfer mechanism and luminescence dynamics were investigated in the framework of the lifetime of the excited states of Eu3+ and Tb3+. The results imply that the present phosphor with multicolor emission might be promising for optoelectronic applications.