Transition-metal oxide nanoparticles are a class of materials that offer a wide range of technological applications due to their special catalytic, electronic, and optical properties. These features are used, for example, in solar technology and in the field of printable electronics. In this context, in particular aluminum-doped zinc oxide (AZO), which is characterized in addition to good mechanical stability and low electrical resistance by special electrochemical properties, offers great potential as a transparent conductor for solar cells, touch panels, displays or light emitting diodes.
The prerequisite for the use of nanoscale AZO devices on an industrial scale is the production of defined reproducible nanomaterials with specific particle properties in terms of size, shape, morphology and doping level for adjusting the optical properties (bandgap energies) and the functionality of the resulting AZO thin films. This requires precise knowledge of the relationship between material specific and structural influences along the entire process chain as well as their effect on the performance of the thin films.
The objective of the research project funded by the DFG, which consists of a cooperation between the Institute of Particle Technology (iPAT) of the TU Braunschweig and the Institute of Mechanical Process Engineering (IMVM) of the KIT, is therefore the analysis of the influence of structural particle properties on the non-aqueous sol Gel synthesis of defined AZO nanocrystals along the entire process chain: This includes both the synthesis conditions and the stabilization of the primary particles, as well as their processing into functional thin films.
In order to investigate the structural properties of the nanoparticles in each process step and in different state forms, the potential of small-angle X-ray scattering (SAXS) metrology for process analysis and control is used, which allows a systematic feedback of the measurement results from the individual process steps with the performance of the layers. In addition, SAXS can be used as a time-resolved method for particle analysis during liquid-phase synthesis (in-situ), so that kinetics can be determined and insights into the mechanisms involved (particle formation, particle growth, aggregation etc.) can be obtained.