Bright red light-emitting devices based on a novel europium complex doped into polyvinylcarbazole

Abstract

The complex (1,10-phenanthroline)tris[4,4,4-trifluoro-1-(9,9-dihexylfluoren-2-yl)-1,3-butanedione] europium(III), Eu(FTA)₃Phen, was synthesized. Devices based on the complex doped into a PVK:PBD host as emitter were fabricated and showed good performance. A double-layer device with a device configuration of ITO/PEDOT:PSS (150 nm)/PVK:PBD:Eu(FTA)₃Phen (80 nm)/Ba (4 nm)/Al (200 nm) with 0.2 wt% Eu(FTA)₃Phen doping concentration emitted a sharp red emission due to the europium(III) ion at 612 nm. The device showed a highest luminance of 114 cd m⁻² at 12.3 V, a maximum external quantum efficiency of 0.41% and a maximum luminance efficiency of 0.44 cd A⁻¹ at 7.5 V. Furthermore, after inserting a TPBI layer, the device performance was greatly enhanced. At 1% w/w Eu(FTA)₃Phen doping concentration, a highest luminance of 465 cd m⁻² at 16.7 V, maximum external quantum efficiency of 4.28% and maximum luminance efficiency of 4.60 cd A⁻¹ at 9.0 V were obtained from a triple-layer device with a configuration of ITO/PEDOT:PSS (150 nm)/PVK:PBD:1 wt% Eu(FTA)₃Phen (80 nm)/TPBI (45 nm)/Ba (4 nm)/Al (200 nm).