Enhanced Photostability Luminescent Properties of Er3+-Doped Near-White-Emitting DyxEr(1–x)-POM Derivatives

A series of DyxEr(1–x)-polyoxometalates (POMs) were successfully synthesized and characterized well by various physicochemical analysis. The structurally isolated compounds exhibit three characteristic emissions at 480 nm (blue, 4F9/2 → 6H15/2 transition), 573 nm (yellow, 4F9/2 → 6H13/2 transition), and 663 nm (red, 4F9/2 → 6H11/2 transition) whose luminescent color coordinates appear in the near-white area in the CIE 1931 chromaticity diagram. Time-resolved emission spectroscopy was used in DyxEr(1–x)-POM to further authenticate energy transfer from the photoexcitation O → M ligand to the metal charge-transfer state of phosphotungstate components to active Dy3+/Er3+ ions and energy transfer between Dy3+ ion and Er3+ ion via intramolecular energy transitions. The relative emission intensity of ∼32%, ∼53%, and ∼85% for Dy-POM, Dy0.9Er0.1-POM, and Dy0.8Er0.2-POM respectively, were obtained under 300 min of UV irradiation, which indicates better photostability of Dy0.8Er0.2-POM. Furthermore, DyxEr(1–x)-POM samples can emit macroscopic white light under blue irradiation.