Alignment of Heptagonal Diimide and Triazine Enables Narrowband Pure-Blue Organic Light-Emitting Diodes with Low Efficiency Roll-Off.
Angew Chem Int Ed Engl
; 62(48): e202312297, 2023 Nov 27.
Article
em En
| MEDLINE
| ID: mdl-37815880
ABSTRACT
The endeavor to develop high-performance narrowband blue organic light-emitting diodes (OLEDs) with low efficiency roll-off represents an attractive challenge. Herein, we introduce a hetero-acceptor design strategy centered around the heptagonal diimide (BPI) building block to create an efficient thermally activated delayed fluorescence (TADF) sensitizer. The alignment of a twisted BPI unit and a planar diphenyltriazine (TRZ) fragment imparts remarkable exciton dynamic properties to 26tCz-TRZBPI, including a fast radiative decay rate (kR ) of 1.0×107 â
s-1 and a swift reverse intersystem crossing rate (kRISC ) of 1.8×106 â
s-1 , complemented by a slow non-radiative decay rate (kNR ) of 6.0×103 â
s-1 . Consequently, 26tCz-TRZBPI facilitates the fabrication of high-performance narrowband pure-blue TADF-sensitized fluorescence OLEDs (TSF-OLEDs) with a maximum external quantum efficiency (EQEmax ) of 24.3 % and low efficiency roll-off even at a high brightness level of 10000 cd m-2 (EQE10000 16.8 %). This showcases a record-breaking external quantum efficiency at a high luminance level of 10000 cd m-2 for narrowband blue TSF-OLEDs.
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MEDLINE
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En
Ano de publicação:
2023
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Article