Spray deposition of organic semiconducting thin-films: Towards the fabrication of arbitrary shaped organic electronic devices

In order to fully exploit the potential of polymer electronics, large-area/low-cost processing technologies suitable for thin-film deposition on arbitrary substrate materials and geometries are necessary. One very promising, yet little examined, deposition technique compatible to large-area industrial-scale processes is provided by spray technology. In this article we present a detailed investigation on the layer formation process during spray deposition of organic thin-films and its relation to solution properties and process parameters. It is demonstrated that the layer formation process can be thought of as a process of successively stacking individual droplets. Microscopy investigations indicate that individual droplets in a spray-coated layer can behave to a certain extent as a continuous layer. The technological framework developed here is successfully applied to the fabrication of organic photo-detecting devices as well as organic thin-film transistors. Gaining insight into the layer formation process represents an important step towards the realization of arbitrary shaped organic electronic devices fabricated by spray deposition.