Energy relay systems for efficient organic light-emitting devices: Influence of formation of exciplex as revealed by photoexcitation

Abstract We investigated potential of performance enhancement for organic light-emitting diodes (OLEDs) by an energy relay system through exciplex formed between a hole transport material (HTM) and an electron transport material (ETM) as revealed by photoexcitation. An enhancement of a dopant (Coumarin 6) emission occurred depending on combination of HTM and ETM, and the dependency can be explained by an overlap integral between an exciplex emission and an absorption of Coumarin 6 as a dopant. Possibility of performance enhancement by the energy relay system was suggested experimentally.