A highly luminescent dinuclear Eu(III) complex based on 4,4'-bis (4',4',4'-trifluoro-1',3'-dioxobutyl)-o-terphenyl for light-emitting diodes

摘要

A dinuclear Eu(III) complex Eu_2(btbt)_3·4H_2O·CH_3CH_2OH·N(CH_2CH_3)_3 was synthesized, where H_2(btbt) was 4,4'-bis (4",4",4",-trifluoro-1",3"-dioxobutyl)-o-terphenyl. The composition and structure of the complex were characterized by elemental analysis, IR, UV-vis and FAB-MS spectroscopy. The complex emits the characteristic red luminescence of Eu~(3+) ion due to the ~5D_0 →~ 7F_J (J=0-4) transitions under ～395 nm-light excitation with good luminescent quantum efficiency (32%) and exhibits high thermal stability (337 ℃). Bright red light-emitting diodes (LEDs) were fabricated by coating the complex onto a～395 nm-emitting InGaN chip. When the mass ratio of the red phosphor to the silicone is 1:30, the efficiency of the fabricated LEDs with the europium complex is 0.98 lm wr~(-1). The CIE chromaticity coordinates of the LEDs are x = 0.6057 and y = 0.3137, which are close to the National Television Standard Committee (NTSC) standard values for red color. The results indicate that the complex may act as a red component in the fabrication of near UV InGaN-based white light-emitting diodes with high color-rendering index.