Organic materials that exhibit thermally activated delayed fluorescence (TADF) are attractive materials for realizing high efficiency OLEDs. A tremendous amount of tailor-made TADF molecules have been reported based on the manipulation of the intramolecular charge transfer as well as the HOMO-LUMO overlap. Beyond this strategy, there is an emerging approach of using exciplex that simply involves intermolecular charge transfer between physically blended electron donor and acceptor molecules. This is because the exciplex-based systems can realize relatively small ΔEST since the electron and hole are located on two different molecules, thereby giving small exchange energy. Consequently, exciplex-based OLEDs have the possibility to maximize the TADF contribution and achieve theoretical 100% internal quantum efficiency. However, research on exciplex-forming materials is still at a growing stage, and consequently, new molecules with remarkable electro and/or photo-physical property are still being explored. Thus, the developments of exciplex-forming systems for achieving high-efficiency and high stability OLED devices are prospective. In this conference, our updated results of new efficient exciplex systems, and exciplex-hosted fluorescent and phosphorescent OLEDs with high efficiency and high stability will be reported.
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