Microscopic origins of charge transport in triphenylene systems

Ian R. Thompson, Mary K. Coe, Alison B. Walker, Matteo Ricci, Otello M. Roscioni, Claudio Zannoni

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We study the effects of molecular ordering on charge transport at the mesoscale level in a layer of ≈9000 hexa-octyl-thio-triphenylene discotic mesogens with dimensions of ≈20×20×60nm3. Ordered (columnar) and disordered isotropic morphologies are obtained from a combination of atomistic and coarse-grained molecular-dynamics simulations. Electronic structure codes are used to find charge hopping rates at the microscopic level. Energetic disorder is included through the Thole model. Kinetic Monte Carlo simulations then predict charge mobilities. We reproduce the large increase in mobility in going from an isotropic to a columnar morphology. To understand how these mobilities depend on the morphology and hopping rates, we employ graph theory to analyze charge trajectories by representing the film as a charge-transport network. This approach allows us to identify spatial correlations of molecule pairs with high transfer rates. These pairs must be linked to ensure good transport characteristics or may otherwise act as traps. Our analysis is straightforward to implement and will be a useful tool in linking materials to device performance, for example, to investigate the influence of local inhomogeneities in the current density. Our mobility-field curves show an increasing mobility with field, as would be expected for an organic semiconductor.
Original languageEnglish
Article number064601
Number of pages12
JournalPhysical Review Materials
Issue number6
Publication statusPublished - 5 Jun 2018


  • Organic electronics
  • Simulation and Modeling
  • Monte Carlo simulations
  • Charge carrier mobility
  • Graph Theory


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