BiVO4 as highly efficient host for near-infrared to visible upconversion

Abstract

BiVO4 is a well-known visible-light-active semiconductor photocatalyst. Here, we report BiVO4 as a highly efficient host material for near-infrared (NIR) to visible frequency upconversion. Various lanthanide ions (Yb, Er, and Tm) doped BiVO4 upconversion phosphors were successfully synthesized through a facile microwave hydrothermal method. As-synthesized samples exhibit intense green, red, and NIR upconversion emissions under 980 nm excitation at power density as low as 0.02 W cm−2. The quantum efficiency for Yb, Er, and Tm triply doped BiVO4 under 2.0 W cm−2 was as high as 2.19% in the 500–850 nm range. Moderately low phonon energy (824 cm−1) of BiVO4 was found to be responsible for the existence of long-lived metastable energy levels leading to efficient upconversion emissions. Potential application of the material for producing latent images and security printing has been demonstrated. The high quantum efficiency of BiVO4 offers an opportunity to develop alternative upconversion materials based on the BiVO4 host for various optical applications.