Detection of Dexter energy transfer process in interface-type OLED via utilizing the characteristic Magneto-electroluminescence response of hot exciton reverse intersystem crossing

The maximum external quantum efficiency (EQE) of the host-guest type organic light-emitting diodes (OLEDs) with interface exciplex as host has been over 36%. However, studies about energy transfer processes occurring from to guest remain lacking. Herein, a strategy is proposed probe in interface-type OLEDs by utilizing characteristic magneto-electroluminescence (MEL) response hot exciton reverse intersystem crossing (T<sub>2, Rub</sub> → S<sub>1, Rub</sub>) Rubrene. Specifically, donor/spacer/accepter (D/S/A) device and D/spacer: x% emitter/A (D/S: 3% Rubrene/A) Rubrene-doped were fabricated. Förster resonance (FRET) process between singlet states exciplex-host Rubrene-guest was demonstrated characterizing photophysical properties donor, accepter, materials. Dexter (DET, T<sub>1, Host</sub> T<sub>2, triplet visualized comparative studying current- temperature-dependent MEL curves D/S/A D/S: Rubrene/A devices, respectively. More importantly, occurrence DET greatly promotes electroluminescence intensity device. Furthermore, we also investigated differences performance devices at low temperature demonstrate again co-existence FRET system. Obviously, this work not only provides promising for probing OLEDs, but paves new way designing high-performance "hot exciton" OLEDs.