| AVS 64th International Symposium & Exhibition | |
| Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic | Tuesday Sessions |
| Session SA+MI-TuM |
| Session: | Overcoming the Temporal and Spatial Limits of X-Ray Scattering Methods for In-Situ Analysis |
| Presenter: | Stephan Pröller, TU Munich, Germany |
| Authors: | S. Pröller, TU Munich, Germany F. Liu, Shanghai Jiao Tong University, PR China C. Zhu, Lawrence Berkeley National Laboratory (LBNL) D. Moseguí González, TU Munich, Germany C. Wang, Lawrence Berkeley National Laboratory (LBNL) E. Schaible, Lawrence Berkeley National Laboratory (LBNL) T.P. Russell, Lawrence Berkeley National Laboratory (LBNL) A. Hexemer, Lawrence Berkeley National Laboratory (LBNL) P. Müller-Buschbaum, Technische Universität München, Germany E.M. Herzig, University Bayreuth, Germany |
| Correspondent: | Click to Email |
The nanomorphology can strongly influence the physical properties of organic thin films. For example, polymer:fullerene blends used in organic solar cells vary significantly in performance depending on the inner film morphology. To allow large-scale production of these devices, control of the nanostructure during the processing of the active layer is important. This firstly needs an understanding of the processes involved during the drying of the film. In a second step we can then manipulate the drying processes to alter the nanostructure. Using an industrial slot-die coater implemented into a synchrotron beamline we have successfully characterized the solidification process of an active layer using grazing incidence small and wide angle X-ray scattering (GISAXS/GIWAXS). Tracking the actual crystallization and aggregation processes on length scales ranging from sub-nanometers to several tens of nanometers reveals how the different growth processes compete with each other leading to the final film morphology. To achieve this, we follow the evolution of the nanostructure with appropriate time-resolution to initially track the solvent removal, followed by the crystallization of the polymer and the aggregation of the fullerene. We find that the morphological evolution can be separated into several subsequent phases that take place independently of the drying speed of the film. The final film morphology, however, depends on the processing speed, because the individual processes compete with each other differently depending on time. Using an environmental control system, we are able to further control the solvent evaporation and hence the structure formation during processing.
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)