| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 175461 | Dyes and Pigments | 2016 | 7 Pages |
•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.
Graphical abstractPure 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 full-size imageDownload as PowerPoint slide
