Issue 15, 2022

Rational design of blocking groups for high triplet energy n-type host materials

Abstract

The effect of blocking groups on the device lifetime and efficiency of blue phosphorescent organic light-emitting diodes (PhOLEDs) was investigated by synthesizing electron transport-type hosts with different blocking groups. Three hosts, 9,9′-(6-(3-(triphenylsilyl)phenyl)-1,3,5-triazine-2,4-diyl)bis(9H-carbazole) (mSi-2CzTrz), 9,9′-(6-([1,1′:3′,1′′-terphenyl]-2′-yl)-1,3,5-triazine-2,4-diyl)bis(9H-carbazole) (tPh-2CzTrz) and 9,9′-(6-(9,9′-spirobi[fluoren]-5-yl)-1,3,5-triazine-2,4-diyl)bis(9H-carbazole) (SBF-2CzTrz) were designed to have both a blocking group and a hole transport-type carbazole group around a triazine core. They had different blocking groups of tetraphenylsilane, terphenyl and spirobifluorene to study their effect. In device applications, the synthesized hosts were used as an electron transport-type host mixed with a hole transport-type 3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) host in PhOLEDs doped with a fac-tris(3-(1-(2,6-diisopropylphenyl)-1H-imidazol-2-yl)benzonitrile)iridium blue phosphorescent emitter. Among the three devices, the mCBP:mSi-2CzTrz mixed host device showed an external quantum efficiency of 22.8% and a device operational lifetime with up to 80% of the initial luminance of over 2000 h at 100 cd m−2 in blue PhOLEDs.

Graphical abstract: Rational design of blocking groups for high triplet energy n-type host materials

Supplementary files

Article information

Article type
Paper
Submitted
23 Dec 2021
Accepted
08 Mar 2022
First published
08 Mar 2022

J. Mater. Chem. C, 2022,10, 5962-5969

Rational design of blocking groups for high triplet energy n-type host materials

J. Ha, S. C. Kim, M. Jung and J. Y. Lee, J. Mater. Chem. C, 2022, 10, 5962 DOI: 10.1039/D1TC06083J

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