An organic electroluminescent device including an anode; a
hole-transporting region disposed over the anode; wherein the
hole-transporting region contains at least one hole-transporting material;
a metal sub-layer disposed within the hole-transporting region; wherein
the metal sub-layer contains at least one metal selected from group 4
through group 16 of the Periodic Table of Elements and the selected metal
has a work-function higher than 4.0 eV; a light-emitting layer formed in
contact with the hole-transporting region for producing light in response
to hole-electron recombination; an electron-transporting layer disposed
over the light-emitting layer; and a cathode disposed over the
electron-transporting layer.
