Optimizing nanoparticles from the gas phase for dispersions and inks for printed electronics

Production of cost-effective printed electronics relies on inks. Inks may be formulated from molecular precursor solutions, which are then converted into the desired material. Alternatively, inks are based on colloidal dispersions of nanoparticles. This review focuses on metal oxide nanoparticles generated by chemical vapor synthesis (CVS) as particle source for ink formulation. The scope and purpose of this review is to look at advantages and challenges of (very) small nanoparticles from the perspective of product design along the process chain. Particle characteristics are identified as quantitative descriptors for particle microstructure which enable product design since they are controllable at each step of the process chain starting from particle synthesis, their determination is facile and they can be directly linked to physical properties and device performance. It is discussed how CVS process parameters influence key particle characteristics such as size, crystallinity, and agglomeration and, therefore, extrinsic materials properties during synthesis relevant for ink and device performance. Subsequent dispersion processes (deagglomeration and stabilization) further alter particle characteristics. Tailoring surface chemistry of CVS-generated nanoparticles through particle-ligand and particle-solvent interactions provides inks of long-term colloidal stability and excellent printability. Finally, laser sintering and its combination with simultaneous inkjet printing are presented as area selective post-treatment processes converting printed nanoparticle films into functional electronic components.