Abstract
In order to explore the triplet–triplet annihilation in cyclometalated iridium complexes, a hetero-triplet iridium complex [Ir(ppy)2pbi] employing two 2-phenylpyridine (Hppy) ligands and one 1,2-diphenyl-1H-benzo[d]-imidazole (Hpbi) ligand with similar triplet energies was synthesized. A device based on Ir(ppy)2pbi exhibited high current efficiency 26.7 cd/A at high doping concentration 12 wt%. More interestingly, the current efficiency was still maintained at 25.8 cd/A when the current density was above 253.2 mA/cm2. The efficiency roll-off was only about 3.4%, much lower than that of traditional cyclometalated iridium complexes. It is proposed that the complicated energy level and unsymmetical ligand in Ir(ppy)2pbi may help to suppress the triplet–triplet annihilation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have