The one-pot synthesis of homoleptic phenylphthalazine iridium(III) complexes and their application in high efficiency OLEDs

A series of homoleptic cyclometalated iridium (III) complexes bearing a 1-phenylphthalazine framework have been synthesized with a facile one-pot method and characterized by X-ray single crystal diffraction. All complexes exhibited orange or red emission peaks at 583–623 nm with short lifetimes of 1.3–2.6 μs and high photoluminescence quantum yields of 41%–82%. These complexes exhibit good thermal stability with high Td of 275–394 °C. The electronic states and orbital distributions of these iridium (III) complexes were studied by density functional theory. These complexes were used as emissive materials in Organic light-emitting diodes (OLEDs). The device based on 2 gave a peak current efficiency and external quantum efficiency (EQE) of 35.1 cd A−1 and 21.2%, respectively. The color coordinates of device based on 3 fully meet that of standard red of the National Television Standards Committee (NTSC). These results suggest that homoleptic phenylphthalazine iridium (III) complexes have potential application as efficient emitters in OLEDs.