Tunable upconversion emission of Ho3+/Yb3+-doped single β-NaYF4 microrod

Abstract In this work, a series of hexagonal phase NaYF 4 : Yb 3+ /Ho 3+ microrods have been successfully synthesized through hydrothermal methods, and their optical properties studied by a confocal microscope equipment with a 980 nm laser. An intense green and red upconversion emissions with candy-like emission pattern are observed from a single NaYF 4 : Yb 3+ /Ho 3+ microrod. As the codoping Ce 3+ ion concentrations increases from 0% to 12% in the microrods, the interesting phenomenon that fluorescence emission of Ho 3+ ion is tuned green to red emission has been obtained. The red-to-green ratio emission of Ho 3+ ions is enhanced about 11-fold, which is due to the two efficient cross-relaxation processes between Ho 3+ and Ce 3+ ions, which leading to the populations increase of the 5 F 5 state. The possible upconversion emission mechanisms are discussed based on the emission spectra of Ho 3+ ions. The current study suggests that the NaYF 4 : Yb 3+ /Ho 3+ microrods with the strong red upconversion emission may have great potential applications in micro-fiber laser, multicolor display, micro-optoelectronic device.