Fabrication of Vertical Molecular Junction Devices with Conductive Polymer Contacts Using a Peeling Method

We present a simple technique for patterning Au top electrodes in vertical molecular junction devices that have the conductive polymer, poly(3,4-ethylene dioxythiophene)-poly(4-styrene sulfonate) (

PSS), as a contact layer between the self-assembled monolayer and the Au top electrode. In this method, a thermally curable photoresist of SU-8 is used to define the areas where the top electrodes are formed. The hydrophobicity and low surface energy of the cured SU-8 facilitates selective deposition of

PSS onto the defined top electrode areas of the device through solution dewetting, and also enables the physical peeling of the Au top electrodes deposited on the SU-8 layers using an adhesion tape. Through this approach, vertical molecular junctions with patterned Au top electrodes can be fabricated without employing the shadow mask evaporation process used in the conventional approach. We processed vertical molecular tunneling devices based on self-assembled alkanedithiol monolayers with an active area of 100 µm2.