Synthesis, characteristics and luminescent properties of a new europium(III) organic complex applied in near UV LED

A novel indane based β-diketone with trifluorobutane in the contraposition, 5-acetylindane-4,4,4-trifluorobutane-1,3-dione (HAITFBD) and its europium(III) ternary complex, Eu(AITFBD)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 in details. The results show that the Eu(III) complex exhibits high thermal stability, wide and strong excitation bands from 300 nm to 425 nm when monitored at 611 nm, which matches well with the 380 nm-emitting InGaN chips. The complex exhibits intense red emission under excitation of near UV light due to the f–f transitions of the central Eu3+ ion. Based on the emission spectrum, the CIE chromaticity coordinates of the LED are calculated as x = 0.63 and y = 0.34, which is suitable to be used as an efficient red phosphor in fabrication of white LEDs. The fluorescence lifetime and the luminescence quantum yield were also measured. The lowest triplet state energy of the primary ligand AITFBD was measured to be 17,730 cm−1, higher than that of the lowest excitation state energy level of the central Eu3+ ion, 5D0, and this suggests that the photoluminescence of the complex is a ligand-sensitized luminescence process (antenna effect). Finally, a bright red light-emitting diode was fabricated by coating the Eu(AITFBD)3phen complex onto a 380 nm-emitting InGaN chip. All the results indicate that Eu(AITFBD)3phen can be applied as a red component for fabrication of near ultraviolet-based white light-emitting diodes.