Doping B(C6F5)3 into poly[N,N‘-bis(4-butylphenyl)-N,N’-bis(phenyl)benzidine] for efficient quantum dot light-emitting diodes: balancing electron-hole injection and diminishing parasitic resistance

Abstract

Low hole mobility and poor film quality always result in poor performance of quantum dot light-emitting diodes (QLEDs). As a p-type dopant into the hole-transport layer (HTL) of the poly[N,N‘-bis(4-butylphenyl)-N,N’-bis(phenyl)benzidine](poly-TPD), B(C6F5)3 is used in hole mobility and film quality improvement for QLEDs. The results show that the hole mobility of the B(C6F5)3 doped poly-TPD layer is risen by 31.6% and excess electron injection is suppressed to balance electron-hole injection. At the same time, B(C6F5)3 doping improves the film quality of both the HTL and quantum dots emitting layer, the parasitic resistance of QLEDs is diminished. The turn-on voltage of the device is reduced from 2.6 V to 2.3 V, and the brightness and current efficiency are increased by 26% and 35.4%, respectively.