Fig. 18

a Chemical structures of emitter dopants and hosts. b Energy transfer mechanism of the TADF emitters with exciplex host (solid arrow indicates FRET and broken line arrow indicates DET). EL spectra of the devices at varying luminance c devices W-1, d W-2, and e W-3, f current density (J–V) vs. luminance characteristics, g PE-luminance and h EQE vs. luminance plots of the three fabricated F-WOLEDs