Abstract:

Two complexes Eu2(btb)3(H2O)4(1) and Eu2(btb)3(phen)2(2)[H2btb=4, 4′-bis(4″, 4″, 4″-trifluoro-1″,3″-dioxobutyl)-biphenyl, phen=1,10-phenanthroline] were synthesized. Their structures were characterized by elemental analysis, IR, UV and FAB-Ms. Both two complexes emit red luminescence, characteristic of the 5D0 → 7FJ (J=0—4) emission bands of Eu3+ under near UV irradiation. Monitored at 614 nm, the strongest excitation wavelength located at 395 nm, which matched to the emission light of InGaN chip. Two red conversion light-emitting diodes(LEDs) devices were fabricated by coating complex onto InGaN-based LED chip that emits 395 nm light. When the mass ratio of the red phosphor to the silicone was 1∶25, the two LEDs CIE chromaticity coordinates(complex 1: x1=0.5210, y1=0.2285; complex 2: x2=0.5835, y2=0.2857) are close to the National Television Standard Committee(NTSC) standard values for red color, the luminescence efficiency of devices are 0.65 lm/W for complex 1, 0.76 lm/W for complex 2. The results indicate that complexes Eu2(btb)3(H2O)4 and Eu2(btb)3(phen)2 can act as red components in the fabrication of white LED.

Key words: Europium complex; Chemical synthesis; Phosphor; Luminescence