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The Role of Reverse Intersystem Crossing Using a TADF‐Type Acceptor Molecule on the Device Stability of Exciplex‐Based Organic Light‐Emitting Diodes
Author(s) -
Nguyen Thanh Ba,
Nakanotani Hajime,
Hatakeyama Takuji,
Adachi Chihaya
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201906614
Subject(s) - oled , intersystem crossing , materials science , excimer , acceptor , optoelectronics , diode , exciton , electron acceptor , photochemistry , molecule , fluorescence , nanotechnology , chemistry , excited state , singlet state , optics , atomic physics , organic chemistry , physics , layer (electronics) , condensed matter physics , quantum mechanics
Exciplex system exhibiting thermally activated delayed fluorescence (TADF) holds a considerable potential to improve organic light‐emitting diode (OLED) performances. However, the operational lifetime of current exciplex‐based devices, unfortunately, falls far behind the requirement for commercialization. Herein, rationally choosing a TADF‐type electron acceptor molecule is reported as a new strategy to enhance OLEDs' operating lifetime. A comprehensive study of the exciplex system containing 9,9′,9′′‐triphenyl‐9H,9′H,9′′H‐3,3′:6′,3′′‐tercarbazole (Tris‐PCz) and triazine (TRZ) derivatives clarifies the relationship between unwanted carrier recombination on acceptor molecules, TADF property of acceptors, and the device degradation event. By employing a proposed “exciton recycling” strategy, a threefold increased operational lifetime can be achieved while still maintaining high‐performance OLED properties. In particular, a stable blue OLED that employs this strategy is successfully demonstrated. This research provides an important step for exciplex‐based devices toward the significant improvement of operational stability.