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The complexes of Tb(III), Eu(III) with 4-(9 H -carbazol-9-yl) benzoic acid ( p -CZBA) have been synthesized, and the compositions and structural characteristics of them have been performed by the element analysis, infrared spectra, thermal analysis, 1 H NMR and fluorescence spectra. Their compositions are Tb( p -CZB) 3 (H 2 O) 2 and Eu( p -CZB) 3 (H 2 O) 2 , respectively. Photoluminescence measurements indicated that p -CZBA itself is a blue emitter under UV radiation. When the effective energy transfer from the organic ligand to the central Tb 3+ ions occurs in the binary complex, strong and characteristic green emission appears due to the 5 D 4 → 7 F j transitions of the 4f electrons of the central Tb 3+ ions. The Tb(III) binary complex is an excellent green-light-emitter, and would be considered as a candidate material for organic light-emitting devices (OLEDs). Eu( p -CZB) 3 (H 2 O) 2 hardly has fluorescence property, this is because the energy of the triplet state of the ligand is not matchable with the energy of the lowest excited state of Eu 3+ . |
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