Iridium(III) Phosphors–Bearing Functional 9?Phenyl?7,9?dihydro?8H?purin?8?ylidene Chelates and Blue Hyperphosphorescent OLED Devices

Herein, a series of blue-emitting Ir(III) phosphors is reported based on the cyclometalating N-heterocyclic carbenes (NHCs), in which typical benzimidazolylidene entity now replaced by new 7,9-dihydro-8H-purin-8-ylidene unit. The two extra-nitrogen atoms that are successfully fined turn emission to true-blue region. As proof concept, both experimental measurement and theoretical calculation these emitters conducted, revealing high photoluminescence quantum yields up 92%, peak maximum located region 420–490 nm, radiative lifetime lower than 1 ?s, depending their stereochemical configuration (i.e., meridional or facial), together with distinctive phenyl appendage. Their photophysical characteristics among best carbene-based blue phosphors. Blue phosphorescent organic light-emitting diode (OLED) using one representative derivative m-2tBu as sole dopant emitter achieves external efficiency (EQE) 17.0%, small roll-off 16% at 1000 cd m?2. Furthermore, hyperphosphorescent OLED 25 wt% sensitizer 2 N7,N7,N13,N13,5,9,11,15-octaphenyl-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diboradinaphtho[3,2,1-de:1?,2?,3?-jk]pentacene-7,13-diamine (?-DABNA) also fabricated, giving excellent performance EQE 22.0% Commission Internationale de l’Éclairage (CIE)xy coordinates (0.120, 0.155).