Aza-triptycene-based homoleptic tris-cyclometalated iridium(III) complexes as highly efficient phosphors in green OLEDs

Abstract

Three homoleptic tris-cyclometalated iridium (III) complexes (Ir1–Ir3) based on a rigid aza-triptycene unit have been synthesized via a novel one-pot method. The coordination arrangement of Ir2 was revealed by single X-ray structural analysis and the molecule showed a facial configuration. These complexes exhibited excellent thermal stability with Td of 454–520 °C. These complexes exhibit strong green phosphorescence emission with high quantum yields of over 70% due to the introduction of aza-triptycene skeleton with rigid steric hindrance reduced intermolecular interactions. Accordingly, the electroluminescence device based on Ir1, Ir2 and Ir3 exhibit high-brightness of 42194, 48807 and 46332 cd m−2, maximum luminous efficiency of 21.0, 24.7 and 28.5 cd A−1 and high EQE of 6.3, 6.8 and 8.9% at a high doping concentration of 30 wt%. Meanwhile, the non-doped green devices based on Ir1, Ir2 and Ir3 give high-brightness of 20571, 15407 and 10707 cd m−2 and luminous efficiency of 8.5, 9.5 and 5.4 cd A−1, respectively. These results suggest that these materials have potential application in OLEDs.