one described above that is cluster like hole injecting regions 605 are formed on the upper and lower sides of the conductive film 604 having a small work function in this case the conductive film 604 having a small work function may be an al li alloy ca or one of other organic conductors as described above the cluster like hole injecting region 605 may be formed by making the conventional hole injecting material into a cluster shape in this case the conventional hole injecting material may be a metal such as au or ito or an inorganic compound conductor or an organic compound having a comparatively small ionization potential next hereinafter the configuration of the electroluminescent layer will be exemplified typically the electroluminescent layer may be constructed of any structural component generally used in the organic el device structure however considering the activation of the device with alternating current bias it is preferable to form electroluminescent layer having bipolar properties as a method for obtaining a bipolar electroluminescent layer one comprises the steps of mixing a hole transporting material and an electron transporting material to form a layer having bipolar properties available hole transporting materials include aromatic amine compounds i e having benzene ring to nitrogen bonds which have been widely used in the art such as 4 4 u2032 bis diphenyl amino biphenyl abbreviated name tad and derivatives thereof 4 4 u2032 bis n 3 methylphenyl n phenyl amino biphenyl abbreviated name tpd and 4 4 u2032 bis n 1 naphthyl n phenyl amino biphenyl abbreviated name u00e1 npd in addition starburst type aromatic amine compounds such as 4 4 u2032 4 u2033 tris n n diphenyl amino triphenylaminine abbreviated name tdata 4 4 u2032 4 u2033 tris n 3 methylphenl n phenyl amino triphenylamine abbrev mtdata may.