TY - JOUR
T1 - Exciton–Exciton Annihilation in Thermally Activated Delayed Fluorescence Emitter
AU - Hasan, Monirul
AU - Shukla, Atul
AU - Ahmad, Viqar
AU - Sobus, Jan
AU - Bencheikh, Fatima
AU - McGregor, Sarah K.M.
AU - Mamada, Masashi
AU - Adachi, Chihaya
AU - Lo, Shih Chun
AU - Namdas, Ebinazar B.
N1 - Funding Information:
The authors thank the Australian Research Council (ARC) (ARC DP160100700), Department of Industry, Innovation and Science (AISRF53765), and JST ERATO (Grant Number JPMJER1305) for financial support. M.H. and V.A. were supported by Australian Government's Australian Postgraduate Award scholarship. A.S. was funded by the UQ's Research and Training Program. This work was performed in part at the Queensland node of the Australian National Fabrication Facility Queensland Node (ANFF-Q)—a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and microfabrication facilities for Australia's researchers.
Funding Information:
The authors thank the Australian Research Council (ARC) (ARC DP160100700), Department of Industry, Innovation and Science (AISRF53765), and JST ERATO (Grant Number JPMJER1305) for financial support. M.H. and V.A. were supported by Australian Government's Australian Postgraduate Award scholarship. A.S. was funded by the UQ's Research and Training Program. This work was performed in part at the Queensland node of the Australian National Fabrication Facility Queensland Node (ANFF‐Q)—a company established under the National Collaborative Research Infrastructure Strategy to provide nano‐ and microfabrication facilities for Australia's researchers.
Publisher Copyright:
© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/7/1
Y1 - 2020/7/1
N2 - Recent studies have demonstrated that in thermally activated delayed fluorescence (TADF) materials, efficient reverse intersystem crossing occurs from nonradiative triplet exited states to radiative singlet excited states due to a small singlet–triplet energy gap. This reverse intersystem crossing significantly influences exciton annihilation processes and external quantum efficiency roll-off in TADF based organic light-emitting diodes (OLEDs). In this work, a comprehensive exciton quenching model is developed for a TADF system to determine singlet–singlet, singlet–triplet, and triplet–triplet annihilation rate constants. A well-known TADF molecule, 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN), is studied under intensity-dependent optical and electrical pulse excitation. The model shows singlet–singlet annihilation dominates under optically excited decays, whereas singlet–triplet annihilation and triplet–triplet annihilation have strong contribution in electroluminescence decays under electrical pulse excitation. Furthermore, the efficiency roll-off characteristics of ACRXTN OLEDs at steady state is investigated through simulation. Finally, singlet and triplet diffusion length are calculated from annihilation rate constants.
AB - Recent studies have demonstrated that in thermally activated delayed fluorescence (TADF) materials, efficient reverse intersystem crossing occurs from nonradiative triplet exited states to radiative singlet excited states due to a small singlet–triplet energy gap. This reverse intersystem crossing significantly influences exciton annihilation processes and external quantum efficiency roll-off in TADF based organic light-emitting diodes (OLEDs). In this work, a comprehensive exciton quenching model is developed for a TADF system to determine singlet–singlet, singlet–triplet, and triplet–triplet annihilation rate constants. A well-known TADF molecule, 3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one (ACRXTN), is studied under intensity-dependent optical and electrical pulse excitation. The model shows singlet–singlet annihilation dominates under optically excited decays, whereas singlet–triplet annihilation and triplet–triplet annihilation have strong contribution in electroluminescence decays under electrical pulse excitation. Furthermore, the efficiency roll-off characteristics of ACRXTN OLEDs at steady state is investigated through simulation. Finally, singlet and triplet diffusion length are calculated from annihilation rate constants.
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U2 - 10.1002/adfm.202000580
DO - 10.1002/adfm.202000580
M3 - Article
AN - SCOPUS:85085701837
SN - 1616-301X
VL - 30
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 30
M1 - 2000580
ER -