Exploration of the influence of structural properties of tailored AZO nanocrystals in the synthesis and processing of functional thin films

• Applicants: Professor Dr. Georg Garnweitner; Professor Dr.-Ing. Hermann Nirschl
• Subject Area: Mechanical Process Engineering
• Term: since 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 313569415

The crystalline n-type semiconductor aluminum-doped zinc oxide (AZO) has a high application potential in the field of semiconductor technology because of its specific properties, e.g. its low electrical resistance, its good mechanical stability and its high transparency in the visible spectral range. Here, AZO will be seen as an attractive alternative to previously used indium-based oxides in the form of liquid dispersions - as so-called transparent conductive oxide (TCO) - in the application areas of thin-film solar cells, light-emitting diodes or in printable electronics. Through collaboration between the AG's Nirschl and Garnweitner, this joint project aims to gain a comprehensive process understanding of the production of particulate thin films using high-quality AZO nanocrystals with tailored crystal shapes and sizes and a defined Al doping to set specific application properties. Here, a holistic view of the overall process by linking the sub-processes: "Production-->Stabilization-->Coating" is provided.During the first funding period, a close cooperation between the participating research groups provided a comprehensive understanding of the ongoing particle formation and growth processes of AZO nanocrystals during their synthesis via the benzyl amine and benzyl alcohol routes. The AG Garnweitner dealt in detail with the benzyl alcohol route and its influence parameters, while the AG Nirschl developed a growth model for the time-resolved description of particulate processes of spherical AZO crystals on the benzyl amine route by means of SAXS analysis. The analysis focus of both AGs was the X-ray scattering method, which provided important information about time-dependent growth and stabilization processes in the nanometer range (<100 nm). The two applicants were able to generate defined crystal shapes and sizes of AZO by selected process control of the respective synthesis routes, which will significantly influence the particulate layer properties as well as the final application properties of the AZO thin films in the further course of the project.The submitted application for a second funding period has the objective of transferring the findings of both AGs from the first funding period relating to the growth and formation processes of AZO nanocrystals via the two synthesis routes to the subsequent process steps (Stabilization-->Coating) and using X-ray scattering of particles to be linked together so that a consideration of the entire process chain up to the production of AZO-modified thin-film solar cells and organic light-emitting diodes with adjustable application properties will be possible.

• DFG Programme: Research Grants