Energy transfer mechanism dominated by the doping location of activators in rare-earth upconversion nanoparticles

Abstract

Research on the energy transfer mechanism of rare-earth-doped upconversion nanoparticles (UCNPs) has been an important area due to the increasing demand for tuning multicolor emission and enhancing the upconversion efficiency; however, because of large energy mismatch, many lanthanide activators, such as Eu³⁺, cannot realize highly efficient near infrared-to-visible upconversion by simple codoping of Yb³⁺. Therefore, introduction of other ions to assist the energy transfer process is required. Herein, we prepared core–shell nanoparticles with different doping locations to investigate the upconversion energy transfer mechanism. The upconversion luminescence (UCL) of core–shell nanoparticles was investigated by steady-state luminescence and time-resolved luminescence spectra. The UCL behaviors in these different multi-activator core–shell nanoparticles were observed. The results revealed different energy transfer channels influenced by the doping location of activators. This study may open up new avenues of structure design for fine-tuning of multicolor UCL for specific applications.