Formation of MgAu alloy cathode by photolithography and its application to organic light-emitting diodes and organic field effect transistors

To make an efficient electron injection electrode by photolithography, we studied MgAu alloy electrodes, which have a low work function and high resistance to humidity and oxygen. The measured work function of MgAu alloy thin film was 3.7 eV, which is comparable with that of a pure Mg layer and ∼0.8 eV lower than that of a pure Au layer. This low work function was maintained even after photolithography, suggesting excellent stability for solvent treatment. Investigating organic field-effect transistor (OFET) characteristics when MgAu alloy comb type source and drain electrodes were used, we successfully obtained n-type FET operation. Furthermore, organic light-emitting diodes (OLEDs) demonstrated the efficient electron injection characteristics of the MgAu alloy cathode, which were similar to those of the conventional MgAg cathode.