Synthesis and electroluminescence properties of new blue dual-core OLED emitters using bulky side chromophores

Using a 1-anthracen-9-yl-pyrene (AP) dual-core emitter, two new emitters of blue light, 1-spiro-9,9'-bifluoren-4-yl-6-(10-spiro-9,9'-bifluoren-4-yl-anthracen-9-yl)-pyrene (DSF-AP) and 1-[2-(9H-carbazol-9-yl)phenyl]-6-[2-(9H-carbazol-9-yl)phenyl-anthracen-9-yl]-pyrene (DCP-AP), were synthesized through boration and the Suzuki aryl-aryl coupling reaction. These two materials exhibited PLmax values at 443 nm and 448 nm in a chloroform solution, and at 458 nm and 463 nm in a thin-film state. EL devices with the synthesized compounds were fabricated in the following configuration: ITO/4,4',4 ''-tris(N-(2-naphthyl)-N-phenylamino)triphenylamine (2-TNATA) (60 nm)/N,N'-bis (naphthalene-1-yl)-N,N'-bis(phenyl)benzidine (NPB) (15 nm)/synthesized blue light-emitting materials (35 nm)/Tris-(8-hydroxyquinoline)aluminum (Alq(3)) (20 nm)/lithium fluoride (LiF) (1 nm)/Al (200 nm). Compared with the device made using an AP core lacking side groups, the device made with DCP-AP displayed 31% higher luminance efficiency (resulting in a value of 4.37 cd/A) and 32% higher power efficiency (to yield 1.93 lm/W), as well as a high external quantum efficiency (3.64%). (C) 2016 Elsevier Ltd. All rights reserved.