The Influential Mechanism of Driving Scheme and Interfacial Barrier on the Lifetime of Deep Blue Fluorescent Organic Light-Emitting Diodes

Enhancing the lifetime of organic light-emitting diodes (OLEDs) is essential for their industrial application. Here, the influence of different driving schemes and interfacial barrier on the degradation rate of the deep blue fluorescent OLEDs is investigated. The results reveal that the driving schemes, which are constant current driving, constant voltage driving, and pulsed current driving schemes, strongly affects the lifetime of OLEDs. The lifetime of LT (90) (90% drop of the brightness) under constant voltage driving is the shortest (156 h) due to the high equivalent resistance. On the contrary, the LT (90) of the OLED under pulsed current driving is the longest (807 h), which is attributed to a low built-in electric field resulted from the decreased accumulation of carriers. Meanwhile, through decreasing the interfacial barrier by doping light emitting layer in electron transporting layer and/or hole transporting layer to modulate the charge accumulation at the interface, the lifetime of OLEDs under pulsed current driving was further increased. The LT (90) of the device increases by 1.84 times to as long as 1483 h, which is the record to the best of our knowledge. This work sheds light on the mechanism of increasing the lifetime of OLEDs and facilitates their industrial application.