Stephan Pröller2 Oliver Filonik2 Margret Eva Thordardottir2 Daniel Mosegui Gonzalez3 Eric Schaible4 Peter Müller-Buschbaum3 Chenhui Zhu4 Cheng Wang4 Alexander Hexemer4 Eva Herzig1 2

2, Technische Universität München, Garching, , Germany
3, Technische Universität München, Garching, , Germany
4, Lawrence Berkeley National Laboratory, Berkeley, California, United States
1, Universität Bayreuth, Bayreuth, , Germany

The properties of many thin films are closely linked with material performance. For industrial applications printing functional thin films is of high relevance. We have developed a set-up to print functional materials under various controlled deposition environments to understand and influence the structure formation in printed thin films. [1] Using examples from thin film photovoltaic systems we gain insight into crystallization processes important for device operation. Our controlled deposition process can be carried out in various multi-modal measurement environments including the use of synchrotron radiation.
We use the advanced scattering techniques grazing incidence wide and small angle x-ray scattering (GISAXS/GIWAXS) to investigate in-situ, the structure formation in printed active layers of organic solar cells using an industrial slot-die coater. [2] We can follow the evolution of thin film morphology with appropriate time-resolution to initially track the solvent removal, followed by the crystallization of the polymer and the aggregation of the fullerene. The morphological evolution can be separated into several subsequent phases that take place independently of the drying speed of the film. We can manipulate the processing using different drying times, either by temperature or saturated gas atmosphere and directly observe the changes on the structural development. Furthermore, we can apply this approach to other promising material systems.
Such measurements are highly valuable for understanding the structure formation processes in material systems of interest for industry, where stable, reproducible fabrication conditions are essential.
[1] S. Pröller, D. Moseguí González, C. Zhu, E. Schaible, C. Wang, P. Müller-Buschbaum, A. Hexemer, E. M. Herzig, Review of Scientific Instruments. 88: 066101 (2017)
[2] S. Pröller, F. Liu, C. Zhu, C. Wang, T.P. Russell, A. Hexemer, P. Müller-Buschbaum, E.M. Herzig, Advanced Energy Materials, 6: 1501580 (2016)