A novel europium(III)–imidazol–diketonate–phenanthroline complex as a red phosphor applied in LED

A β-diketone, 4-imidazol-4,4,4-trifluorobutane-1,3-dione (HIDTFBD) and the corresponding europium(III) complex Eu(IDTFBD)3phen were designed and synthesized, where phen was 1,10-phenanthroline. The complex was characterized by IR, UV–visible, thermogravimetric analysis (TGA) and photoluminescence (PL) spectroscopy. Monitored at 610 nm, the Eu(III) complex exhibited a strong and wide excitation band between 320 and 420 nm due to the formation of a big π-conjugated system in the complex molecule. Under near UV-light excitation, the complex showed strong red emission of Eu3+ ion due to the 5D0–7FJ (J = 0–4) transitions. The fluorescence lifetime and the luminescence quantum yield were also measured. Finally, a bright red light-emitting diode was fabricated by coating the europium ternary complex onto an ~ 395 nm-emitting InGaN chip, and the LED exhibited appropriate CIE chromaticity coordinates in red area. All these results suggest that the Eu(III) complex is a promising candidate as red component for fabrication of near UV-based white light-emitting diodes.