Synthesis and optoelectronic properties of a dinuclear iridium (III) complex containing a picolinic acid derivative by nonconjugated linkage with a D-A-D core

A novel dinuclear iridium (Ⅲ) complex containing a non- conjugated bridging picolinic acid ligand of (C8TPAPhOC2FIrpic)2BT with a D-A-D core was synthesized and characterized, in which the D-A-D core consists of benzo[c][1,2,5]thiadiazole (BT) and triphenylamino (TPA) units. Its optophysical, electrochemical and electroluminescent characteristics were primarily studied. It is found this dinuclear iridium (Ⅲ) complex exhibited similar photoluminescent and electroluminescent profiles, but higher brightness and efficiency in compared with the picolinic acid ligand in the single-emissive-layer organic light-emitting devices. The maximum luminance of 7404 cd/m2 and current efficiency of 0.81 cd/A was obtained in the (C8TPAPhOC2FIrpic)2BT-based devices. The efficient energy transfer is observed from the terminal iridium complex unit to the picolinic acid ligand. This work demonstrates that the picolinic acid ligand with a D-A-D core can facilitate dinuclear iridium (III) complex to exhibit the ancillary ligand-based red emission.