Intermolecular energy transfer and photostability of luminescence-tuneable multicolour PMMA films doped with lanthanide–β-diketonate complexes

Abstract

It is reported in this work the preparation, characterisation and photoluminescence study of poly(methylmethacrylate) (PMMA) thin films co-doped with [Eu(tta)3(H2O)2] and [Tb(acac)3(H2O)3] complexes. Both the composition and excitation wavelength may be tailored to fine-tune the emission properties of these Ln3+–β-diketonate doped polymer films, exhibiting green and red primary colours, as well as intermediate colours. In addition to the ligand–Ln3+ intramolecular energy transfer, it is observed an unprecedented intermolecular energy transfer process from the 5D4 emitting level of the Tb3+ ion to the excited triplet state T1 of the tta ligand coordinated to the Eu3+ ion. The PMMA polymer matrix acts as a co-sensitizer and enhances the overall luminescence intensity of the polymer films. Furthermore, it provides considerable UV protection for the luminescent species and improves the photostability of the doped system.