Photoluminescence of ternary europium complexes based on unsymmetrical diketone

In order to investigate the influence of doping samarium (III) (Sm³⁺) ions on the photoluminescence properties of ternary europium complexes, Eu_1−xSm_x(NPPD)₃·(DPQ) and Eu_1−xSm_x(NPPD)₃·(NPT) (HNPPD, 1-(naphthalen-2-yl)-3-phenylpropane-1,3-dione; DPQ, dipyridobenzoquinone; NPT, 5-nitro-1,10-phenanthroline; x = 0·0, 0·1, 0·3, 0·5, 0·7, 0·9, 1·0) were synthesized by the reaction of lanthanide chloride with ligands in stoichiometry. The obtained complexes were characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet/visible spectroscopy and luminescence spectroscopy. The study of photoluminescence properties showed intensely red emission due to the ⁵D₀ → ⁷F_j transitions of the central europium (III) (Eu³⁺) ions, indicating that the triplet state energy of ligands is suitable for sensitizing the luminescence of europium (III) ions. Furthermore, the emission efficiency varied with doping of samarium (III) ions due to energy transfer from samarium (III) ions to europium (III) ions. The photoluminescene intensity of Eu_1−xSm_x(NPPD)₃·(DPQ) were obviously higher than those of Eu_1−xSm_x(NPPD)₃·(NPT). Among all the prepared complexes, Eu_0·7Sm_0·3(NPPD)₃·(DPQ) shows the highest photoluminescene quantum yield, which would have the potential application for organic light-emitting diodes.