Polymorphism and structure formation in copper phthalocyanine thin films
| Autor: | Takuya Hosokai, Clemens Zeiser, Alexander Gerlach, Linus Pithan, Berthold Reisz, Alexander Hinderhofer, Giuliano Duva, Martin Hodas, Jakub Hagara, Frank Schreiber, Valentina Belova, Peter Siffalovic |
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| Rok vydání: | 2021 |
| Předmět: |
GenX
Materials science X-ray reflectivity 02 engineering and technology Crystal structure Triclinic crystal system 010402 general chemistry grazing-incidence X-ray diffraction 01 natural sciences General Biochemistry Genetics and Molecular Biology polymorphism morphology Molecule Thin film organic semiconductors Silicon oxide atomic force microscopy reciprocal space mapping 021001 nanoscience & nanotechnology Research Papers 0104 chemical sciences Organic semiconductor Reciprocal lattice Crystallography thin films 0210 nano-technology |
| Zdroj: | 'Journal of Applied Crystallography ', vol: 54, pages: 203-210 (2021) Journal of Applied Crystallography |
| ISSN: | 1600-5767 0021-8898 |
| Popis: | This X-ray diffraction study proves that two α polymorphs of copper pthalocyanine (CuPc) co-exist in vacuum-deposited thin films and provides possible molecular configurations by excluded-volume considerations. Furthermore, atomic force microscopy images together with a simple MATLAB simulation show that elevated substrate temperatures facilitate the downward diffusion of CuPc molecules during film growth and lead to a smoother surface. Many polymorphic crystal structures of copper phthalocyanine (CuPc) have been reported over the past few decades, but despite its manifold applicability, the structure of the frequently mentioned α polymorph remained unclear. The base-centered unit cell (space group C2/c) suggested in 1966 was ruled out in 2003 and was replaced by a primitive triclinic unit cell (space group P 1). This study proves unequivocally that both α structures coexist in vacuum-deposited CuPc thin films on native silicon oxide by reciprocal space mapping using synchrotron radiation in grazing incidence. The unit-cell parameters and the space group were determined by kinematic scattering theory and provide possible molecular arrangements within the unit cell of the C2/c structure by excluded-volume considerations. In situ X-ray diffraction experiments and ex situ atomic force microscopy complement the experimental data further and provide insight into the formation of a smooth thin film by a temperature-driven downward diffusion of CuPc molecules during growth. |
| Databáze: | OpenAIRE |
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