TY - JOUR
T1 - Origin of efficiency roll-off for FIrpic based blue organic light-emitting diodes and implications on phosphorescent molecule design
AU - Wang, Jia
AU - Zhang, Han
AU - Ji, Wenyu
AU - Zhang, Hanzhuang
AU - ZHU, Fu Rong
N1 - This work was supported by the program of the National Natural Science Foundation of China (Nos. 61205025, 11474131, 11274304, and 11274142) and the Research Grants Council of Hong Kong Special Administrative Region, China, Project No. T23-713/11.
Publisher Copyright:
© 2015 The Japan Society of Applied Physics.
PY - 2015/10/1
Y1 - 2015/10/1
N2 - This work reports our effort on understanding the efficiency roll-off in blue phosphorescent organic light-emitting diodes (OLEDs), based on bis[3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)]-iridium (FIrpic) doped in 4,4-N,N-dicarbazole-biphenyl (CBP) host. The performance of a set of blue phosphorescent OLEDs with different FIrpic dopant concentrations was analyzed. Unusually, the device having a 30-nm-thick pure FIrpic emissive layer with a high luminous efficiency of 7.76 cd/A at 100mA/cm2 was obtained. Theoretical calculation, based on the density functional theory, reveals that the exciton self-quenching process is suppressed due to the strong Coulomb repulsion between FIrpic molecules. It is found that the efficiency roll-off in FIrpic-based OLEDs is closely related to the exciton quenching induced by the CBP+ radical cations that are present in the CBP host.
AB - This work reports our effort on understanding the efficiency roll-off in blue phosphorescent organic light-emitting diodes (OLEDs), based on bis[3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)]-iridium (FIrpic) doped in 4,4-N,N-dicarbazole-biphenyl (CBP) host. The performance of a set of blue phosphorescent OLEDs with different FIrpic dopant concentrations was analyzed. Unusually, the device having a 30-nm-thick pure FIrpic emissive layer with a high luminous efficiency of 7.76 cd/A at 100mA/cm2 was obtained. Theoretical calculation, based on the density functional theory, reveals that the exciton self-quenching process is suppressed due to the strong Coulomb repulsion between FIrpic molecules. It is found that the efficiency roll-off in FIrpic-based OLEDs is closely related to the exciton quenching induced by the CBP+ radical cations that are present in the CBP host.
UR - https://www.scopus.com/pages/publications/84943224576
U2 - 10.7567/JJAP.54.101601
DO - 10.7567/JJAP.54.101601
M3 - Journal article
AN - SCOPUS:84943224576
SN - 0021-4922
VL - 54
JO - Japanese Journal of Applied Physics
JF - Japanese Journal of Applied Physics
IS - 10
M1 - 101601
ER -