Energy level alignment in organic-based three-layer structures studied by photoelectron spectroscopy

The alignment of energy band edges at interfaces in three-layer structures, important in polymer-based electroluminescent devices, have been studied u sing photoelectron spectroscopy. Careful choice of the materials allows inv estigation of the role of the substrate work function. These results are in agreement with the energy level diagram commonly assumed for the metal/pol ymer/metal structure, with the potential drop over the polymer layer being equal to the difference between the work functions of the metal contacts. D irect indication of the alignment of the electrochemical potential across t he three-layer structure has been observed by photoelectron spectroscopy. ( C) 2000 American Institute of Physics. [S0021-8979(00)06801-3].