Highly efficient upconversion single red emission of hollow cubic α-NaErF4 nanoparticles by Mn/Yb heavy doping

Lanthanide doped upconversion (UC) nanoparticles show enormous potential in the biomedical field. However, the interference color emission and low photoluminescence quantum yield (PLQY) still limit its practical application. Here, we present a facile strategy to get alpha-NaErF4:40%Mn hollow cubic nanoparticles with singleband red emission. Furthermore, on the basis of this hollow cubic morphology, high efficiency red emission of Er3+ ions is obtained by heavy doping of the sensitizer (Yb3+ ions). The emission intensity of alpha-NaErF4:40%Mn, 40%Yb hollow cubic nanoparticles is 114,929 times higher than that of beta-NaErF4 nanoparticles under 980 nm laser excitation, as well as the red emission intensity increase by 44 times under 808 nm laser excitation. High color pure and high luminous UC alpha-NaErF4:40%Mn, 40%Yb hollow cubic nanoparticles make them superior as biomarkers for in cell and vivo bioimaging. This will provide a good application prospect of UC nanoparticles in the biological field.