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Nanoscale chemical analysis of beam-sensitive polymeric materials by cryogenic electron microscopy |
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| Authors: | Zino J. W. A. Leijten Maarten J. M. Wirix Sorin Lazar Wouter Verhoeven O. Jom Luiten Gijsbertus de With Heiner Friedrich |
| Affiliation: | 1. Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands Center for Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands;2. Materials and Structural Analysis, Thermo Fisher Scientific, Eindhoven, The Netherlands;3. Coherence and Quantum Technology group, Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands;4. Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands Coherence and Quantum Technology group, Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands;5. Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands |
| Abstract: | Nanoscale chemical analysis of functional polymer systems by electron microscopy, to gain access into degradation processes during the materials life cycle, is still a formidable challenge due to their beam sensitivity. Here a systematic study on the different stages of degradation in a P3HT-PCBM organic photovoltaic (OPV) model system is presented. To this end pristine samples, samples with (reversibly) physisorbed oxygen and water and samples with (irreversibly) chemisorbed oxygen and water are imaged utilizing the full capabilities of cryogenic STEM-EELS. It is found that oxygen and water are largely physisorbed in this system leading to significant effects on the band structure, especially for PCBM. Quantification proves that degradation concomitantly decreases the amount of CC bonds and increases the amount of C O C bonds in the sample. Finally, it is shown that with a pulsed electron beam utilizing a microwave cavity, beam damage can be significantly reduced which likely extends the possibilities for such studies in future. |
| Keywords: | band structure cryogenic (scanning) transmission electron microscopy degradation pathways electron energy loss spectroscopy organic photovoltaics pulsed electron beams |