Enhanced Electroluminescence of Polymer Light-Emitting Diodes with Direct Polyaniline Synthesized Anodes

We report the current-voltage and the electroluminescence characteristics of the light-emitting diodes based on poly [2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with indium-tin oxide (ITO) anodes and the diodes in which a layer of polyaniline (PANI) is synthesized directly on a layer of self-assembled monolayers formed by N-phenylaminopropyltrimethoxysilane above the ITO. The results show that the PANI layer reduces Schottky energy barrier and enhances the electroluminescence intensity. We believe that the insertion of the PANI layer causes dipole layers established on the surface resulting in the reduction of the energy barrier. The PANI layer also affects the electron-hole transition probability of the active layer enhancing the brightness of the devices dramatically.