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.

Graphical abstractHighly 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 full-size imageDownload as PowerPoint slide