Built-in voltage in organic light-emitting diodes with a use of Li2O/Al cathode.

An effect of bilayer cathode Li2O/Al system was studied in Alq3 based organic light-emitting diodes with a variation of Li2O layer thickness from 0 to 10 nm. The device was made in a structure of ITO/(TPD)/Alq3/Li2O/Al. Current density-luminance-voltage (J-L-V) characteristics and a built-in voltage of the device were measured at ambient conditions.