@article{HeStolteBurschkaetal.2015,
  author    = {He, Tao and Stolte, Matthias and Burschka, Christian and Hansen, Nis Hauke and Musiol, Thomas and K{\"a}lblein, Daniel and Pflaum, Jens and Tao, Xutang and Brill, Jochen and W{\"u}rthner, Frank},
  title     = {Single-crystal field-effect transistors of new Cl\(_{2}\)-NDI polymorph processed by sublimation in air},
  series = {Nature Communications},
  volume    = {6},
  journal   = {Nature Communications},
  number    = {5954},
  doi       = {10.1038/ncomms6954},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149255},
  year      = {2015},
  abstract  = {Physical properties of active materials built up from small molecules are dictated by their molecular packing in the solid state. Here we demonstrate for the first time the growth of n-channel single-crystal field-effect transistors and organic thin-film transistors by sublimation of 2,6-dichloro-naphthalene diimide in air. Under these conditions, a new polymorph with two-dimensional brick-wall packing mode (\(\beta\)-phase) is obtained that is distinguished from the previously reported herringbone packing motif obtained from solution (\(\alpha\)-phase). We are able to fabricate single-crystal field-effect transistors with electron mobilities in air of up to 8.6 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\alpha\)-phase) and up to 3.5 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\beta\)-phase) on n-octadecyltriethoxysilane-modified substrates. On silicon dioxide, thin-film devices based on \(\beta\)-phase can be manufactured in air giving rise to electron mobilities of 0.37 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\). The simple crystal and thin-film growth procedures by sublimation under ambient conditions avoid elaborate substrate modifications and costly vacuum equipment-based fabrication steps.},
  language  = {en}
}
@article{HeWuD'Avinoetal.2018,
  author    = {He, Tao and Wu, Yanfei and D'Avino, Gabriele and Schmidt, Elliot and Stolte, Matthias and Cornil, J{\´e}r{\^o}me and Beljonne, David and Ruden, P. Paul and W{\"u}rthner, Frank and Frisbie, C. Daniel},
  title     = {Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-04479-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227957},
  year      = {2018},
  abstract  = {Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.},
  language  = {en}
}