Abstract
Time-resolved luminescence measurements are invaluable for understanding light-emitting materials but are difficult to perform on operating organic light-emitting diodes (OLEDs) because the light generated by the OLED can disturb common time-resolved techniques. We show that frequency-domain luminescence can be used to overcome this problem, and apply it to study efficiency roll-off in OLEDs. We measure the exciton lifetime of a phosphorescent OLED based on the emitter bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate) iridium(III) (Ir(MDQ)2(acac)) whilst it is operating. By driving the OLED continuously at current densities of up to 128 mA/cm2, we observe that the exciton lifetime decreases with increasing current density as a result of triplet-polaron annihilation (TPA). The measurement presented can guide the development of new materials and device structures with improved efficiency at high brightness.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
