The present invention provides layered hole injection structures including
one or more layers of fullerenes for application in an organic
electroluminescent device. The layered structures include a bi-layered
structure including an electrically conductive layer serving as
electrical contact to external circuit and a fullerene layer sandwiched
between the conductive layer and a hole transport layer. The layered
structure may also includes a tri-layered structure stacked sequentially
including a first electrically conductive layer, a fullerene layer and a
hole injection layer material selected from thermally stable molecules
such as CuPc. The layered structure may also include a four-layered
structure stacked sequentially including a first electrically conductive
layer, a fullerene layer on the conductive layer, a noble metal layer on
the fullerene layer and another fullerene layer on the noble metal layer.