Inkjet printing of photonic structures and thin-film transistors based on evaporation-driven material transportation and self-assembly

Inkjet printing has emerged from a digital graphic arts printing technology to become a versatile tool for the patterned deposition of functional materials. This thesis contributes to the research in the area of functional inkjet printing by focusing on two different topics: (i) inkjet printing of colloidal suspensions to study the principles of deposit formation and to develop deposits with photonic properties based on self-assembly, and (ii) the development of a reliable manufacturing process for all-inkjet-printed thin-film transistors, highlighting the importance of selection of materials and inks, print pattern generation, and the interplay between ink, substrate and printing conditions. (i) Colloidal suspensions containing nanospheres were applied as ink formulation in order to study the fundamental processes of layer formation and to develop structures with periodically arranged nanospheres allowing the modulation of electromagnetic waves. Evaporation-driven self-assembly was found to be the main driver for the formation of the final deposit morphology. Fine-tuning of inkjet process parameters allows the deposition of highly ordered structures of nanospheres to be arranged as monolayer, multilayer or even three-dimensional assemblies with a microscopic spherical shape. (ii) This thesis demonstrates the development of a manufacturing process for thin-film transistors based on inkjet printing. The knowledge obtained from the study with the colloidal nanospheres is used to generate homogeneous and continuous thin films that are stacked well-aligned to each other to form transistors. Industrial printheads were applied in the manufacturing process, allowing for the up-scaling of the manufacturing by printing of several thousands of devices, and thus the possibility to study the process yield as a function of printing parameters. The discrete droplet-by-droplet nature of the inkjet printing process imposes challenges on the control of printed patterns. Inkjet print