Efficient green electroluminescent devices based on iridium complex with wide energy gap complexes as sensitizers

• Efficient green electroluminescent devices were fabricated.
• Blue iridium complexes with wide energy gap were utilized as sensitizers.
• Sensitizer molecules within light-emitting layer function as electron trappers.
• Sensitizer with lower energy levels has better sensitization effect.

In this work, electroluminescent (EL) performances of a green iridium complex (tfmppy)2Ir(tpip) were significantly improved by utilizing wide energy gap iridium complexes FK306 and FIrpic as sensitizers. Due to the low-lying energy levels, the co-doped FK306 or FIrpic molecules function as electron trappers, which are helpful in balancing holes and electrons on (tfmppy)2Ir(tpip) molecules and in broadening exciton recombination zone. Consequently, the co-doped devices displayed high EL efficiencies and slow efficiency roll-off. Compared with FIrpic, FK306 acts as a more effective sensitizer because of its relatively lower energy levels. Consequently, highly efficient green EL device with maximum current efficiency, power efficiency and brightness up to 102.29 cd/A (external quantum efficiency (EQE) of 25.3%), 88.67 lm/W and 96,268 cd/m2, respectively, was realized by optimizing the co-doping concentration of FK306. Even at the practical brightness of 1000 cd/m2, EL current efficiency up to 92.93 cd/A (EQE = 23%) can still be retained.

Highly efficient green EL device with maximum current efficiency, power efficiency and brightness up to 102.29 cd/A (external quantum efficiency (EQE) of 25.3%), 88.67 lm/W and 96,268 cd/m2, respectively, was realized by optimizing the co-doping concentration of a wide energy gap blue iridium complex FK306 as sensitizer.Figure optionsDownload as PowerPoint slide