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Protecting Benzylic CH Bonds by Deuteration Doubles the Operational Lifetime of Deep‐Blue Ir‐Phenylimidazole Dopants in Phosphorescent OLEDs
Author(s) -
Bae Hye Jin,
Kim Jong Soo,
Yakubovich Alexander,
Jeong Jinhoon,
Park Sangho,
Chwae Jun,
Ishibe Satoko,
Jung Yongsik,
Rai Virendra Kumar,
Son WonJoon,
Kim Sunghan,
Choi Hyeonho,
Baik MuHyun
Publication year - 2021
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202100630
Subject(s) - phosphorescence , oled , dopant , materials science , common emitter , photochemistry , optoelectronics , doping , fluorescence , nanotechnology , chemistry , optics , physics , layer (electronics)
Much effort has been dedicated to increase the operational lifetime of blue phosphorescent materials in organic light‐emitting diodes (OLEDs), but the reported device lifetimes are still too short for the industrial applications. An attractive method for increasing the lifetime of a given emitter without making any chemical change is exploiting the kinetic isotope effect, where key CH bonds are deuterated. A computer model identifies that the most vulnerable molecular site in an Ir‐phenylimidazole dopant is the benzylic CH bond and predicts that deuteration may hamper the deactivation pathway involving CH/D bond cleavage notably. Experiments show that the device lifetime until the initial luminance diminishes to 70% (LT 70 ) of a prototype phosphorescent OLED device can be doubled to 355 hours with a maximum external quantum efficiency of 25.1% at 1000 cd m −2 . This is one of the best operational performances of blue phosphorescent OLEDs observed to date in a single stacked cell.