Gravure printed Ag/conductive polymer electrodes and simulation of their electrical properties

In this paper, some practical issues related to the manufacturing, and design criteria related to the application in devices of a hybrid silver grid/poly (3,4-ethylenedioxythiophene) semi-transparent electrode are discussed. The electrodes are fabricated by gravure printing and screen printing. Experiments showed that defects in the printed grid due to imperfect ink transfer from the gravure roll to the substrate are detrimental to electrode performance. Various parameters like gravure cell design, printing speed, or particle size of the ink were investigated to minimize the fraction of defects and to obtain highly conductive grids. It will be demonstrated that overprinting of the lines is a feasible strategy to minimize the number of defects without noticeably broadening the lines. While a defect-free grid is prerequisite for such a hybrid device, for applications even stronger design criteria hold. That is addressed in the second part of the paper, where the electrical properties of the printed grids are simulated. With two exemplary device architectures, namely an organic light-emitting diode (OLED) and an organic photovoltaic cell, artificial load layers are integrated into the device structure, and potential maps are calculated. The examples show how simulations can be deployed to design and optimize grid electrodes for a specific application.