Novel carbazole-based multifunctional materials with a hybridized local and charge-transfer excited state acting as deep-blue emitters and phosphorescent hosts for highly efficient organic light-emitting diodes
In this work, two carbazole- and benzo[ d ]oxazole-based novel multifunctional materials with a hybridized local and charge-transfer (HLCT) characteristic, namely, OCI and OCT , which could act as deep-blue fluorophors and phosphorescent hosts, were first designed and synthesized. Both OCI and OCT d...
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Published in | Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 9; no. 18; pp. 5899 - 597 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Cambridge
Royal Society of Chemistry
14.05.2021
|
Subjects | |
Online Access | Get full text |
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Summary: | In this work, two carbazole- and benzo[
d
]oxazole-based novel multifunctional materials with a hybridized local and charge-transfer (HLCT) characteristic, namely,
OCI
and
OCT
, which could act as deep-blue fluorophors and phosphorescent hosts, were first designed and synthesized. Both
OCI
and
OCT
display meritorious thermal stability with a glass transition temperature (
T
g
) as high as 139 and 137 °C, respectively. The two compounds also reveal excellent bipolar carrier transport ability and emit deep-blue emission with photoluminescence quantum yields (PLQY) of 34.5% and 14.0%, respectively. Used as blue fluorophors,
OCI
- and
OCT
-based non-doped devices exhibit a very low turn-on voltage (
V
on
) of 3.0 V and realize deep-blue emission with peaks located at 438-453 nm, and the optimized OCI-based device achieve the maximum external quantum efficiency (
η
ext,max
) reaching 3.19%. Remarkably, doped blue devices show even deeper blue emission at 424 and 428 nm and the optimized OCI-based device achieves a significantly improved
η
ext,max
of 5.06% with CIE
y
< 0.04, which could rank among the deepest blue HLCT fluorophors. Additionally, green phosphorescent OLEDs hosted by
OCI
and
OCT
reveal a low
V
on
of 2.7 V with maximum current efficiencies (
η
c,max
) of 49.43 cd A
−1
(
η
ext,max
of 14.11%) and 52.81 cd A
−1
(
η
ext,max
of 15.57%), respectively, which are superior to that of
CBP
(
V
on
of 3.0 V,
η
c,max
of 51.76 cd A
−1
and
η
ext,max
of 12.88%). The superb electroluminescence (EL) performance of
OCI
and
OCT
as deep-blue HLCT emitters and phosphorescent hosts demonstrates that they have great potential for industrial applications.
Two novel multifunctional HLCT materials, namely
OCI
and
OCT
, were presented and they proved to be better green hosts than CBP. Acting as a deep-blue emitter, the
OCI
-based device achieved an EQE of 5.06% and CIE
y
< 0.04 with an EL peak at 424 nm. |
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Bibliography: | 10.1039/d1tc00494h Electronic supplementary information (ESI) available. See DOI |
ISSN: | 2050-7526 2050-7534 |
DOI: | 10.1039/d1tc00494h |