Pinhole‐Free Inkjet Printing Strategies for Organic Electronics

Abstract

AbstractInkjet printing is a widely used technique in the field of printed electronics. Yet its reliability is limited because absent droplets induced by defective, e.g., clogged, nozzles can lead to pinholes in the printed layers causing a reduction of the quality of printed films or a breakdown of the functionality in microelectronic devices. Therefore, pinholes in inkjet‐printed layers need to be avoided. In this study the origins for pinholes in inkjet‐printed films are examined. It is found that single missing droplets cannot lead to pinholes but certain formations can. This paper presents the corresponding responsible combinations of defective nozzles necessary to create a pinhole. To enable a statistical approach the pinhole occurrence probabilities are computed depending on the number of broken nozzles as well as quality factors and step sizes with a Monte Carlo simulation. The model shows that by choosing the right print strategy the pinhole probability can be reduced by three orders of magnitude. Finally, a novel print strategy is suggested, which is not yet supported by default printer settings but can reduce the pinhole probability even further by a factor of over 2000 in total. This represents the smallest pinhole occurrence probability ever achieved.