Ohmic Contact Formation to PEDOT-PSS Films Using Graphite-Clay

Metal-to-semiconductor contacts are present in every semiconductor (conducting polymer) device which can behave either as a Schottky diode (rectifying junction) or as an ohmic contact. Whether a contact is ohmic or rectifying depends not only on the difference in work functions of the contact metal and semiconductor but also on the contact surface defects. Many methods and processes are being developed to make ohmic contacts to organic semiconductors. In this paper, we report simple and inexpensive methods to achieve ohmic contacts to PEDOT-PSS which otherwise makes rectifying contact to copper. It has been shown that by coating the contact metal with graphite-clay using commercially available pencils, ohmic contacts can be produced. It is also demonstrated that by dispersing graphite powder in PEDOT-PSS on copper ohmic contacts can be made.