Fabrication and Experimental Evaluation of the PEDOT:PSS/ZnO Diode Interface

ZnO is a seminal wide and direct bandgap semiconductor used in various devices like transparent thin film transistors which require interfacing with other semiconductors and conductors. Particularly, it is prevalent to form devices based on the interfaces between ZnO and organic semiconductors, which are easy to deposit and do not interfere with their transparency. Here, we report the results of our experimental work on the fabrication and assessment of the interface of PEDOT:PSS/ZnO structure. Fabricated devices show strongly asymmetric conductivity, while the I-V characteristics of the device strongly depend on the technique used for the PEDOT:PSS deposition on $\mathbf{Z n O}$ thin films. $\mathbf{Z n O}$ layers are fabricated by sputtering under an oxygen plasma onto a zinc substrate, and PEDOT:PSS/ZnO interface is formed by several techniques of a) drop casting, b) dip coating, and c) flake pressing. In comparison, the devices fabricated using the latter method result in diodes with considerably higher rectification ratio. For the formation of PEDOT:PSS/ZnO contacts with almost symmetric conductivity, drop casting appears to be more promising.