Synthesis, opto-physics, and electroluminescence of cyclometalated iridium (III) complex with alkyltrifluorene picolinic acid

To improve the opto-physics, electroluminescence, and dispersibility of iridium (III) complexes in polymer light-emitting devices, we synthesized and characterized two red-emitting heteroleptic cyclometalated iridium (III) complexes of (Piq)2Ir(Tfl-pic) and (Piq)2Ir(Brfl-pic), in which Piq is 1-phenylisoquinoline, Tfl-pic and Brfl-pic are alkyltrifluorene- and dibromoalkylfluorene-containing picolinic acid derivatives bridged with alkoxy chain, respectively. Compared to (Piq)2Ir(pic) and (Piq)2Ir(Brfl-pic), (Piq)2Ir(Tfl-pic) exhibited higher thermal stability, better dispersibility and excellent quantum efficiency. High-efficiency red emission with a maximum current efficiency of 6.28 cdA−1 and a maximum EL peak at 608 nm was obtained in the (Piq)2Ir(Tfl-pic)-doped devices using a blend of poly(9,9-dioctylfluorene) and 2-(4-biphenyl)-5-(4-tert -butylphenyl)-1,3,4-oxadiazole as a host matrix.