High-performance OLEDs based on 4,5-diaza-9,9′-spirobifluorene ligated rhenium(I) complex with enhanced steric hindrance

Highly efficient and emitter concentration insensitive phosphorescent electroluminescent devices based on a novel rhenium(I) Re(I)] complex, i.e., (4,5-diaza-9,9′-spirobifluorene)Re(CO)₃Br (Re-DSBF), were established. Non-doped device based on Re-DSBF as emitter exhibited outstanding performances with the peak luminance of 8531 cd m⁻² and maximum current efficiency of 16.8 cd A⁻¹, which were the highest reported to date for non-doped phosphorescent electroluminescent devices based on Re(I) emitters. Such excellent performances are closely related to the steric hindrance, large Stokes shift, and short luminescent lifetime of Re-DSBF complex. The luminescent mechanisms of those devices were also investigated.