Bis-tridentate Ir(III) Phosphors and Blue Hyperphosphorescence with Suppressed Efficiency Roll-Off at High Brightness

Abstract

Narrowband blue emitters are indispensable in achieving ultrahighdefinition OLED displays that satisfy the stringent BT 2020 standard. Hereby, a series of bis-tridentate Ir(III) complexes bearing electron-deficient imidazo [4,5-b]pyridin-2ylidene carbene coordination fragments and 2,6-diaryloxy pyridine ancillary groups were designed and synthesized. They exhibited deep blue emission with quantum yields of up to 89% and a radiative lifetime of 0.71 μs in the DPEPO host matrix, indicating both the high efficiency and excellent energy transfer process from the host to dopant. The OLED based on Irtb1 showed an emission at 468 nm with a maximum external quantum efficiency (EQE) of 22.7%. Moreover, the hyper-OLED with Irtb1 as a sensitizer for transferring energy to terminal emitter v-DABNA exhibited a narrowband blue emission at 472 nm and full width at half-maximum (FWHM) of 24 nm, a maximum EQE of 23.5%, and EQEs of 19.7, 16.1, and 12.9% at a practical brightness of 100, 1000, and 5000 cd/m 2 , respectively.

Selective syntheses of homoleptic Ir(iii) complexes bearing di-CF3-functionalized benzoimidazol-2-ylidenes for generation of blue phosphorescence

“…Similar manipulation has been documented in Ir( iii ) carbene complexes such as m -Ir(tfp_tz) 3 11–13 and its analogues. 14,15 Furthermore, Zysman-Colman and co-workers have also reported mer -arranged, homoleptic and blue Ir( iii ) phosphors comprising 1-methyl-3-(4-(trifluoromethyl)phenyl)-imidazol-2-ylidene chelates, cf ., m -Ir(tfpmi) 3 and its analogue. 16 Next, they switched to similar Ir( iii ) complexes containing a sterically demanding benzyl (or 2,4,6-trimethylbenzyl) appendage on carbene chelates, cf ., m -Ir(tfpi_Bn) 3 .…”