Inkable CF3-functionalized benzothiazole/benzimidazole-Ir(III) complexes for efficient bilayer-inkjet-printed OLEDs

• Inkable CF 3 -bt/bm-Ir(III) complexes were designed and synthesized. • The substituent effect and position effect of CF 3 group were well investigated. • These Ir(III) complexes had good ink-jet printability. • The Ir(III)-doped bilayer-inkjet-printed OLEDs demonstrated the promising performances. The inkjet-printed organic light-emitting diodes (OLEDs) are gradually gaining popularity due to their low cost, free vacuum environment, patterning, and large-area display capability, but inkable phosphors are yet less reported. In order to develop inkable phosphorescent luminescent material, the introduction of the strong electron-withdrawing CF 3 in the C^N ligand of iridium(III) [Ir(III)] complexes is a wise choice. Herein, a serials of phosphorescent Ir(III) complexes consisting of 2-phenybenzothiazole/1,2-diphenylbenzimidazole with the introduction of CF 3 group at ortho (o)/meta (m)/para (p) position of the phenyl ring abbreviated as (obt) 2 Ir(acac), (mbt) 2 Ir(acac), (pbt) 2 Ir(acac), (obm) 2 Ir(acac), (mbm) 2 Ir(acac), (pbm) 2 Ir(acac), respectively, were designed and synthesized. The substituent effect and position effect of CF 3 group based on the Ir(III) complexes were investigated in all aspects. The bilayer-inkjet-printed OLEDs with those phosphors were studied and showed promising electroluminescent performances. Among them, the OLEDs with (obt) 2 Ir(acac)/(obm) 2 Ir(acac) emitter exhibited the maximum external quantum efficiency of 3.7%/3.3%. In addition, the vacuum-deposited OLEDs with those Ir(III) phosphors as emitters were further investigated and demonstrated outstanding device performance.