Fig. 3. Resonant transfer of the exciplex energy to energy acceptor molecules.

(A) EL spectrum of an energy transfer–type device at a luminance of 200 cd/m². The dashed line shows the PL spectrum of a 2 wt % DBP:mCBP co-deposited film. Inset: Schematic illustration of the emission layer. (B) Time-resolved EL decay curves measured for a device with d = 50 Å at room temperature. EL was accumulated after exposure of each OLED to a pulse voltage with a duration of 5 μs. Inset: Accumulated emission spectra for total (black), prompt (red), and delayed (blue) components.