Multicolor upconversion luminescence of Ln-doped Sc₂O₃ achieved by coordination geometry mediated RE-MOFs molecular alloys as precursor

The wide application of lanthanide ion (Ln³⁺) doped upconversion (UC) luminescent materials in optical communication, color display, anti-counterfeiting, bioimaging, and so on have fuelled increasing demand for new host materials and rational control over the emission profiles. In this study, we serendipitous obtained the unexpected Sc/Ln codoped rare earth metal-organic frameworks (RE-MOFs) molecular alloys (MAs) based on rare earth oxalate (Ln = Yb/Tm and Yb/Ho) even though they show three different crystal structures. Moreover, the crystal structure of RE-MOFs MAs changes at varying Sc:Ln mole ratio. We achieved the corresponding Ln³⁺ doped Sc₂O₃ by pyrolysis of the RE-MOFs MAs precursor, and investigated the UC luminescence property. The codoped rare earth oxide (REO) shows characteristic blue color emission for Yb/Tm, and green color emission for Yb/Ho doped Sc₂O₃ microcrystals respectively. This study here provides useful theoretical information for enriching novel Ln³⁺ doped UC luminescent materials.