@article{WeberFrankBommeletal.2012,
  author    = {Weber, Cornelia and Frank, C. and Bommel, Sebastian and Rukat, Tammo and Leitenberger, Wolfram and Sch{\"a}fer, Peter and Schreiber, Frank and Kowarik, Stefan},
  title     = {Chain-length dependent growth dynamics of n-alkanes on silica investigated by energy-dispersive x-ray reflectivity in situ and in real-time},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {136},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  number    = {20},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.4719530},
  pages     = {7},
  year      = {2012},
  abstract  = {We compare the growth dynamics of the three n-alkanes C36H74, C40H82, and C44H90 on SiO2 using real-time and in situ energy-dispersive x-ray reflectivity. All molecules investigated align in an upright-standing orientation on the substrate and exhibit a transition from layer-by-layer growth to island growth after about 4 monolayers under the conditions employed. Simultaneous fits of the reflected intensity at five distinct points in reciprocal space show that films formed by longer n-alkanes roughen faster during growth. This behavior can be explained by a chain-length dependent height of the Ehrlich-Schwoebel barrier. Further x-ray diffraction measurements after growth indicate that films consisting of longer n-alkanes also incorporate more lying-down molecules in the top region. While the results reveal behavior typical for chain-like molecules, the findings can also be useful for the optimization of organic field effect transistors where smooth interlayers of n-alkanes without coexistence of two or more molecular orientations are required.},
  language  = {en}
}
@article{KowarikGerlachLeitenbergeretal.2007,
  author    = {Kowarik, Stefan and Gerlach, Andreas and Leitenberger, Wolfram and Hu J, Witte and W{\"o}ll, Christoph and Schreiber, Frank},
  title     = {Energy-dispersive X-ray reflectivity and GID for real-time growth studies of pentacene thin films},
  issn      = {0040-6090},
  doi       = {10.1016/j.tsf.2006.12.020},
  year      = {2007},
  abstract  = {We use energy-dispersive X-ray reflectivity and grazing incidence diffraction (GID) to follow the growth of the crystalline organic semiconductor pentacene on silicon oxide in-situ and in real-time. The technique allows for monitoring Bragg reflections and measuring X-ray growth oscillations with a time resolution of 1 min in a wide q-range in reciprocal space extending over 0.25-0.80 angstrom(-1), i.e. sampling a large number of Fourier components simultaneously. A quantitative analysis of growth oscillations at several q-points yields the evolution of the surface roughness, showing a marked transition from layer-by-layer growth to strong roughening after four monolayers of pentacene have been deposited. (c) 2006 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{SchwarzeSchellhammerOrtsteinetal.2019,
  author    = {Schwarze, Martin and Schellhammer, Karl Sebastian and Ortstein, Katrin and Benduhn, Johannes and Gaul, Christopher and Hinderhofer, Alexander and Toro, Lorena Perdigon and Scholz, Reinhard and Kublitski, Jonas and Roland, Steffen and Lau, Matthias and Poelking, Carl and Andrienko, Denis and Cuniberti, Gianaurelio and Schreiber, Frank and Neher, Dieter and Vandewal, Koen and Ortmann, Frank and Leo, Karl},
  title     = {Impact of molecular quadrupole moments on the energy levels at organic heterojunctions},
  series = {Nature Communications},
  volume    = {10},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-019-10435-2},
  pages     = {9},
  year      = {2019},
  abstract  = {The functionality of organic semiconductor devices crucially depends on molecular energies, namely the ionisation energy and the electron affinity. Ionisation energy and electron affinity values of thin films are, however, sensitive to film morphology and composition, making their prediction challenging. In a combined experimental and simulation study on zinc-phthalocyanine and its fluorinated derivatives, we show that changes in ionisation energy as a function of molecular orientation in neat films or mixing ratio in blends are proportional to the molecular quadrupole component along the p-p-stacking direction. We apply these findings to organic solar cells and demonstrate how the electrostatic interactions can be tuned to optimise the energy of the charge-transfer state at the donor-acceptor interface and the dissociation barrier for free charge carrier generation. The confirmation of the correlation between interfacial energies and quadrupole moments for other materials indicates its relevance for small molecules and polymers.},
  language  = {en}
}