Solvation induced morphological effects on the polymer/metal contacts

Polymer/metal interfaces play an important role in determining the performa nce of polymer based electronic devices. For most polymer diodes, one of th e polymer/metal contacts is usually formed by spin casting a polymer soluti on onto a metal electrode; we call it polymer-on-metal (POM) contact. The o ther polymer/metal contact is usually formed by vacuum deposition of metal vapor onto the polymer surface; we call it metal-on-polymer (MOP) contact. In this article, we present evidence that the formation of the POM contact is strongly influenced by the processing of polymer thin films. The POM con tact has a greater energy barrier for carrier injection than the MOP contac t. The morphology of the polymer thin films, i.e., the relative arrangement s of the side groups and conjugated backbone, significantly affects the int erfacial characteristics. We also present a simple method of evaluating the morphological effects at the contact. (C) 2001 American Institute of Physi cs.