Luminescent and thermal properties of a novel red-emitting silicon fluoride acrylate-Eu(III) copolymer for white LEDs

A red-emitting silicon fluoride acrylate (SFA)-Eu(III) copolymer was prepared based on water-in-oil emulsion polymerization method. Its photoluminescence including the temporal decay was studied in addition to the thermal properties. Of the emissions due to the ⁵D₀ → ⁷F_J (J = 0-4) transitions of Eu³⁺ ions, an intense red emission due to ⁵D₀ → ⁷F ₂ transition was observed at 618 nm under the 395 nm excitation, together with a weak ⁵D₀ → ⁷F₀ emission at 580 nm. Compared with some commercial phosphor, the SFA-Eu(III) copolymer also have a higher QE value. From the optical properties it was suggested that Eu³⁺ ions were located at the disordered non-inversion Eu³⁺ sites in the copolymer. The glass transition temperature (T_g) was estimated about -51.5 °C from a differential scanning calorimetric curve, while chemical decomposition was estimated to start from 385 °C from a thermogravimetry analysis curve. Taking into account the thermal stability in a wide temperature range from -51.5 °C to 385 °C, the SFA-Eu(III) copolymer is expected to act as a potential red component for near-UV excited white LEDs.