Er<sup>3+</sup>-Sensitized Upconversion/Down-Shifting Luminescence in Metal–Organic Frameworks
Yao Xie, Guotao Sun, Jiwei Li, Renrui Sun, Lining Sun
Abstract
Photoluminescent metal–organic frameworks (MOFs) are used as optical materials with excellent properties, of which the lanthanide-doped MOFs are able to emit in a broad region from visible to near-infrared due to their unique 4f-orbital electronic structure. Herein, Er 3+ and Y 3+ ions are selected as the metal centers of the MOFs and Er 3+ is used as a sensitizer to absorb 980 nm excitation light. At the same time, Er 3+ ions also act as activators that emit upconverting visible light and down-shifting near-infrared light. In addition, Tm 3+, Ho 3+, and Eu 3+ ions were individually doped into the Er 3+ -doped MOFs to investigate the variation of energy-transfer paths in the presence of different lanthanide activators. Finally, the pathway of energy transfer in these Er 3+ -sensitized luminescent-MOFs was summarized. This work provides new insights for further development of both upconversion and down-shifting luminescence of MOFs.