Quantitative analysis of intermolecular interactions in orthorhombic rubrene
Venkatesha R. Hathwar,
Mattia Sist,
Mads R. V. Jørgensen,
Aref H. Mamakhel,
Xiaoping Wang,
Christina M. Hoffmann,
Kunihisa Sugimoto,
Jacob Overgaard,
Bo Brummerstedt Iversen
Affiliations
Venkatesha R. Hathwar
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Mattia Sist
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Mads R. V. Jørgensen
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Aref H. Mamakhel
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Xiaoping Wang
Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, PO Box 2008 - MS 6475, Oak Ridge, TN 37831, USA
Christina M. Hoffmann
Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, PO Box 2008 - MS 6475, Oak Ridge, TN 37831, USA
Kunihisa Sugimoto
Japan Synchrotron Radiation Research Institute, I-I-I, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
Jacob Overgaard
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Bo Brummerstedt Iversen
Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
Rubrene is one of the most studied organic semiconductors to date due to its high charge carrier mobility which makes it a potentially applicable compound in modern electronic devices. Previous electronic device characterizations and first principles theoretical calculations assigned the semiconducting properties of rubrene to the presence of a large overlap of the extended π-conjugated core between molecules. We present here the electron density distribution in rubrene at 20 K and at 100 K obtained using a combination of high-resolution X-ray and neutron diffraction data. The topology of the electron density and energies of intermolecular interactions are studied quantitatively. Specifically, the presence of Cπ...Cπ interactions between neighbouring tetracene backbones of the rubrene molecules is experimentally confirmed from a topological analysis of the electron density, Non-Covalent Interaction (NCI) analysis and the calculated interaction energy of molecular dimers. A significant contribution to the lattice energy of the crystal is provided by H—H interactions. The electron density features of H—H bonding, and the interaction energy of molecular dimers connected by H—H interaction clearly demonstrate an importance of these weak interactions in the stabilization of the crystal structure. The quantitative nature of the intermolecular interactions is virtually unchanged between 20 K and 100 K suggesting that any changes in carrier transport at these low temperatures would have a different origin. The obtained experimental results are further supported by theoretical calculations.
