Reducing the photo-bleaching effect of a new europium complex embedded in styrene butadiene copolymer

A highly luminescent europium complex obtained with two different ligands, succinimide (SI) and 2-thenoyltrifluoroacetone (TTA), was synthetized with different TTA concentrations. The photoluminescence (PL) emission from these materials corresponds to the characteristic inter-electronic energy level transitions of the Eu3+ ions. However, the excitation spectrum is strongly dependent on the presence of TTA, having an optimum response when 0.75 mmol of this compound is added to the EuL3(H2O)3 complex. The quantum yield obtained by these powders were around 72%±1.7% indicating an optimum sensitization of these complex. The EuL3TTA complex with the best PL properties was embedded in a styrene butadiene copolymer (SBC) film, produced by the drop casting method, obtaining similar PL behavior at different concentrations, the highest intensity was observed at 1.2% (w/v) of EuL3TTA complex and the quantum yield of these composite films was 60.5%±2%. These films were exposed to continuous UV irradiation and after 141 h no photo-bleaching effect was observed in contrast with the EuL3TTA complex that exhibited a noticeable photoluminescence intensity degradation at much shorter exposure times. Both the Eu-complexes and the composite films were characterized by FT-IR, XRD, SEM and fluorescence spectroscopy.