Tuning the Photoluminescence Properties of β-NaYF4:Yb,Er by Bi3+ Doping Strategy

The low luminous efficiency of upconversion materials limits their practical applications in various fields. The present study focuses on the efficient upconversion enhancement of β-NaYF 4 :Yb,Er induced by Bi 3+ doping. The XRD and SEM results show that introducing Bi 3+ into the matrix lattice changes the microstructure and particle size of the crystal. The photoluminescence spectra show that at 6% Bi 3+ doping, the red and green emission intensities are enhanced by 12 and 8 times, respectively. The reason could be the lattice distortion caused by Bi 3+ doping, breaking the partial forbidden transition of rare-earth ions. The fluorescence lifetime measurement reveals that the Bi 3+ doping changes the environment around erbium ions, affecting the energy level lifetime of erbium ions, explaining the luminescence dynamics law. The present study provides a facile route to achieve nano/microstructures with intense upconversion luminescence with potential applications in optoelectronic devices.