Highly efficient pure red organic light-emitting devices based on tris(1-phenyl-isoquinoline) iridium(III) with another wide gap iridium(III) complex as sensitizer

• Pure red electroluminescent devices with stepwise energy levels were designed and fabricated.
• Wide energy gap iridium complex with matched triplet energy was chosen as sensitizer.
• The incorporation of sensitizer facilitates the balance of carriers on emitter molecules.
• The incorporation of sensitizer broadens the recombination zone.

In this work, we report the realization of highly efficient pure red organic co-doped electroluminescent device with tris(1-phenyl-isoquinoline) iridium(III) (Ir(piq)3) and iridium(III) bis(4,6-(difluorophenyl)pyridinato-N,C2′)picolinate (FIrpic) as emitter and sensitizer, respectively. By selecting 4,4′,4″-Tri(9-carbazoyl)triphenylamine and 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine as host materials, a series of devices with single or double light-emitting layer(s) were fabricated and investigated. The well-known wide gap blue emitter FIrpic, which possesses low-lying energy levels, was co-doped minutely into electron dominant light-emitting layer. Compared with reference devices, co-doped devices displayed significant improvement of device performances attributed to improved carriers' balance and broadening recombination zone. Finally, the 0.3 wt% co-doped double light-emitting layers device obtained the maximum brightness, current efficiency, power efficiency and external quantum efficiency up to 28,031 cd/m2, 14.89 cd/A, 12.99 lm/W and 9.0%, respectively. Even at the certain brightness of 1000 cd/m2, EL efficiency as high as 12.06 cd/A can be retained by the same device.

Pure red electroluminescent devices with stepwise energy levels were designed and fabricated by co-doping the wide energy gap iridium complex as sensitizer. Significantly improved device performances were realized attributed to improved carriers' balance and broadening recombination zone.Figure optionsDownload as PowerPoint slide