Electrical doping for high performance organic light emitting diodes

摘要

Novel p-dopants of ReO_3 and CuI, and an n-dopant of Rb_2CO_3 have been developed. Among many other p-dopants, ReO_3 possesses superior characteristics of low temperature deposition, efficient charge generation and increasing the device lifetime. The absorption intensity of charge transfer complexes and current-voltage characteristics revealed that charge generation in p-doped hole transporting layers is more effective when the work function of the dopant is larger. High performance OLEDs have been fabricated using the p- and n-dopants, including the low driving voltage p-i-n phosphorescent OLEDs, high power efficiency of tandem OLEDs using ReO_3 doped NPB/ReO_3 (1 nm)/Rb_2CO_3 doped Bphen as the interconnection unit, and top emission OLEDs using CuI doped NPB as the hole injection layer from Ag electrode.