Blue Iridium (III) Phosphorescent OLEDs with High Brightness Over 10 000 cd m-2 and Ultralow Efficiency Roll-Off

Herein, a family of six [3+2+1] coordinated 2-(2 ',4 '-difluorophenyl) pyridine-based Iridium(III) complexes with intermolecular interactions have been designed to improve their emission properties. These molecular interactions have been regarded as an effective way to suppress non-radiative decay and enhance the photoluminescence quantum yield (PLQY) of the light-emitting materials. Specifically, complex 3 functionalized with new -CF3 ligand exhibits PLQY of up to 100%, and the emission peak at approximate to 485 nm with short excited-state lifetime down to 1 mu s. Therefore, the blue phosphorescent organic light-emitting diode (OLED) based on complex 3 dopant exhibits excellent performance with a maximum external quantum efficiency of 22.0% and low efficiency roll-off. Upon increasing the current density to 250 mA cm(-2), high brightness value of 53 400 cd m(-2) is achieved, which is not attainable with the similar molecular structure that we have reported recently, indicating the importance of the presence of the (C-F center dot center dot center dot H/C(sic)N center dot center dot center dot H) interactions. Given the well-overlapping of the emission spectra of these Iridium(III) complexes and absorption spectrum of v-DABNA emitter, complex 3 has been successfully applied as a sensitizer for v-DABNA-based OLED, and a maximum current efficiency of 27.13 cd A(-1) with high brightness level of up to 10 000 cd m(-2) have been achieved.