Rubidium-Carbonate-Doped 4,7-Diphenyl-1,10-phenanthroline Electron Transporting Layer for High-Efficiency p-i-n Organic Light Emitting Diodes

Abstract

We investigated the electrical properties and charge transport mechanisms of a rubidium-carbonate -doped 4,7-diphenyl-1,10-phenanthroline (Bphen) electron transporting layer (ETL). The electron-only devices and photoemission spectroscopy analysis revealed that the formation of doping-induced gap states dominantly contributes to the improvement of carrier transport characteristics of the doped system. High-efficiency green phosphorescent p-doping/intrinsic/n-doping (p-i-n) organic light emitting diodes were demonstrated using the -doped Bphen ETL and rhenium oxide -doped -diphenyl--bis(-biphenyl)--diamine hole transporting layer, exhibiting an external quantum efficiency of 19.2%, power efficiency of , and low operation voltage of at .