The structure of the organic devices and the principal materials used to demonstrate the sensitized energy transfer are shown in the inset of Fig. 1 . In the second device, the sensitizer was completely omitted in order to examine direct energy transfer from the donor, CBP, to the acceptor, DCM2. The DCM2 emission efficiency of the device containing the phosphorescent sensitizer is significantly higher than its fluorescent analogue. The external quantum efficiencies of DCM2 emission in the three devices. The emission spectra of the OLEDs are shown in Fig.
All devices show energy transfer to the fluorescent dye.
The spectra of the three electroluminescent devices fabricated in this work. The resulting emission was measured using a streak camera. The decrease in the triplet lifetime as a result of energy transfer to the fluorescent acceptor is advantageous. Not only does it increase the transient response of the system, but it should also reduce the probability of triplet-triplet annihilation. Thus, it is expected that this multi-stage energy transfer will reduce the quenching of triplet states, thereby further enhancing the potential efficiency of sensitized fluorescence.