Suppressing triplet exciton quenching by regulating the triplet energy of crosslinkable hole transport materials for efficient solution-processed TADF OLEDs

Crosslinkable hole transport materials (HTMs) with high triplet energies would have a balance of carrier injection into the emitting material layer, suppressing the triplet exciton quenching and resulting in high-performance solution-processed organic light-emitting diode (OLED) devices. Two novel c...

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Bibliographic Details
Published in:Science China materials 2023, Vol.66 (1), p.291-299
Main Authors: Yan, Yifei, Zhang, Fei, Liu, Hongli, Li, Xianggao, Wang, Shirong
Format: Article
Language:English
Subjects:
Carrier injection
Chemistry and Materials Science
Chemistry/Food Science
Crosslinking
Current efficiency
Diamines
Dibenzothiophene
Excitons
Fluorescence
Materials Science
Organic light emitting diodes
Quantum efficiency
Quenching
Thermal resistance
Thermal stability
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Summary:Crosslinkable hole transport materials (HTMs) with high triplet energies would have a balance of carrier injection into the emitting material layer, suppressing the triplet exciton quenching and resulting in high-performance solution-processed organic light-emitting diode (OLED) devices. Two novel crosslinkable HTMs with different central units, N 2 , N 8 -di- p -tolyl- N 2 , N 8 -bis(4-vinylphenyl)dibenzo[b,d]thiophene-2,8-diamine (V- p -DBT) and N 2 , N 8 -di- p -tolyl- N 2 , N 8 -bis(4-vinylphenyl)dibenzo[b,d]furan-2,8-diamine (V- p -DBF), were designed and synthesized. The use of dibenzothiophene and dibenzofuran units increases the torsion angle compared with the commonly used N, N ′-di- p -tolyl- N, N ′-bis(4-vinylphenyl)-[1,1′-biphenyl]-4,4′-diamine (V- p -TPD), leading to high triplet energies of 2.57 and 2.64 eV, respectively. The triplet energies of V- p -DBT and V- p -DBF effectively suppress triplet exciton quenching. Furthermore, the crosslinked HTM layer showed excellent solvent-resistant abilities and high thermal stability. An outstanding maximum current efficiency (CE max ) of 79.94 cd A −1 and maximum external quantum efficiency (EQE max ) of 24.35% were obtained by V- p -DBF-based green thermally activated delayed fluorescent (TADF) OLEDs. This work provides a new molecular design strategy for achieving efficient solution-processed TADF OLEDs.
ISSN:2095-8226
2199-4501
DOI:10.1007/s40843-022-2121-0