ABSTRACT
A better solution consists in increasing the weaker injection. This is obtained by the insertion of an injecting layer sandwiched between the organic film and the electrode associated to the minority charge carrier.
Starting from the anode, the construction of a hole-injection layer (HIL) with a low ionization potential lowers the barrier controlling the injection of holes. A very thin layer (2-10 um) of a molecular material such as copper phtalocyanine (CuPc) [9], polyaniline (PANT) [10] or 3,4,9, 1 0-perylen etetracarboxylic dianhydride (PTCDA) [11] is commonly used. Symmetrically an electron-injection layer (EIL) just below the cathode perform the same functions but for negative carriers. It is built by doping few nanometers of the organic
layer with highly reactive metal such as strontium, samarium, lithium and its salts [12].
