cm5b02012_si_004.cif (26.77 kB)
Dibenzothiophene-Based Phosphine Oxide Host and Electron-Transporting Materials for Efficient Blue Thermally Activated Delayed Fluorescence Diodes through Compatibility Optimization
dataset
posted on 2015-07-28, 00:00 authored by Chaochao Fan, Chunbo Duan, Ying Wei, Dongxue Ding, Hui Xu, Wei HuangThermally activated delayed fluorescence
(TADF) organic light-emitting
diodes arise from the development of high-performance host materials
and carrier transporting materials fitting for TADF dyes with optimized
respective properties and interplays, making simultaneous performance
improvement and device structure simplification feasible. In this
work, a highly efficient blue TADF diode with simplified four-layer
structure was successfully achieved by utilizing bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone
(DMAC-DPS) as blue emitter, 4,6-bis(diphenylphosphoryl)dibenzothiophene
(DBTDPO) as host, and 4,6-bis(diphenylphosphoryl)dibenzothiophene
sulfone (46DBSODPO) as electron-transporting layer. The
compatibilities between DBTDPO and DMAC-DPS and DBTDPO and 46DBSODPO were
optimized with respect to configuration, polarity, energy level, and
interfacial interaction, resulting in the unchanged roughness of ∼0.25
nm before and after doping, high photoluminescence quantum yield over
85%, and reduced interfacial exciplex emissions. With the similar
triplet excited energy (T1) of ∼3.0
eV but inferior electrical properties compared to its analogues 28DBSODPO and 37DBSODPO, besides the homogeneity
with DBTDPO, 46DBSODPO suppressed the formation
of interfacial exciplex and dipole for efficient exciton confinement
and electron injection and transportation, in virtue of the steric
effects of its ortho-substituted phosphine oxide
groups. Consequently, DBTDPO and 46DBSODPO endowed their DMAC-DPS based four-layer
devices with the state-of-the-art performance, for example, the maximum
external quantum efficiency over 16%, which was more than two-fold
of those of conventional electron-transporting material 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene
(TmPyPB). This design strategy about material compatibility
could pave a way for developing high-performance blue TADF diodes
with simplified configurations.