Hot exciton transition for organic light-emitting diodes: tailoring excited-state properties and electroluminescence performances of donor-spacer-acceptor molecules
The photophysical, electrochemical and electroluminescent properties of newly synthesized blue emitters with donor-π-acceptor geometry, namely, 4'-(1-(naphthalen-1-yl)-1 -phenanthro[9,10- ]imidazol-2-yl)- , -diphenyl-(2-[1,1'-biphenyl]vinyl)-4-amine (NSPI-TPA), 4'-(1-(2-methylnaphthal...
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Published in | RSC advances Vol. 8; no. 65; pp. 37324 - 37338 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
England
Royal Society of Chemistry
01.01.2018
The Royal Society of Chemistry |
Subjects | |
Online Access | Get full text |
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Summary: | The photophysical, electrochemical and electroluminescent properties of newly synthesized blue emitters with donor-π-acceptor geometry, namely, 4'-(1-(naphthalen-1-yl)-1
-phenanthro[9,10-
]imidazol-2-yl)-
,
-diphenyl-(2-[1,1'-biphenyl]vinyl)-4-amine (NSPI-TPA), 4'-(1-(2-methylnaphthalen-1-yl)-1
-phenanthro[9,10-
]imidazol-2-yl)-
,
-diphenyl-(2-[1,1'-biphenyl]vinyl)-4-amine (MNSPI-TPA), 4-(2-(4'-(diphenylamino)-(2-[1,1'-biphenyl]vinyl)-4-yl)-1
-phenanthro[9,10-
]imidazol-1-yl)-1-naphthalene-1-carbonitrile (SPNCN-TPA) and 4-(2-(4-(9
-carbazol-9-yl)styryl)-1
-phenanthro[9,10-
]imidazol-1-yl)naphthalene-1-carbonitrile (SPNCN-Cz) were analyzed. The conjugation length in the emitters is not conducive to pure emission and hence, a molecular twisting strategy was adopted in NSPI-TPA, MNSPI-TPA, SPNCN-TPA and SPNCN-Cz to enhance pure emission. The emissive state (HLCT) of twisted D-π-A molecules containing both LE and CT (HLCT) states was tuned for high PL (
) (LE) and high exciton utilization (
) (CT) efficiencies by replacing triphenylamine (strong donor) with carbazole (weak donor). Among strong donor compounds, namely, NSPI-TPA, MNSPI-TPA and SPNCN-TPA, the SPNCN-TPA-based device exhibited blue emission (451 nm) with CIE coordinates (0.15, 0.08), maximum current efficiency (
) of 2.32 cd A
, power efficiency (
) of 2.01 lm W
and external quantum efficiency (
) of 3.02%. The device with SPNCN-Cz emitter exhibited higher electroluminescence efficiencies than the SPNCN-TPA-based device, with pure blue emission (443 nm, CIE: 0.15,0.07),
of 3.15%,
of 2.56 cd A
and
of 2.45 lm W
. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 2046-2069 2046-2069 |
DOI: | 10.1039/c8ra07891b |