Er3+-Tm3+-Yb3+ tri-doped CaMoO4 upconverting phosphors in optical devices applications

The structural and optical properties of the Er³⁺-Tm³⁺-Yb³⁺codoped CaMoO₄ phosphors prepared by chemical route have been explored. The crystalline structures of the prepared phosphors have been investigated with the help of X-ray diffraction analysis. The presence of different vibrational modes and absorption bands arising due to the transitions from the ground state to different excited states of rare earth ions have been identified using the Raman and UV-VIS-NIR absorption spectra of the developed phosphor, respectively. The concentration quenching effect on the luminescence property of the prepared materials has been explained in detail. The upconversion luminescence property of the Er³⁺-Tm³⁺-Yb³⁺codoped CaMoO₄ phosphor annealed at different temperatures under 980 nm and 808 nm excitations have been reported. The energy transfer Er³⁺ → Tm³⁺, Yb³⁺ → Er³⁺ and Tm³⁺ has been found to be responsible for efficient UC emission. The dipole-dipole interaction is observed to be responsible for the concentration quenching of the luminescence intensity. The effect of annealing temperature on the upconversion luminescence property has been explained in detail. The results suggest that the developed tri-doped phosphor may be suitable in making the efficient NIR to visible upconverter and lighting based optical devices.