Er 3+ -Sensitized Upconversion/Down-Shifting Luminescence in Metal-Organic Frameworks.

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.