High fidelity computational methods are key for identifying fundamental properties of organic semiconductors. This dissertation focuses on both improving computational bottle necks in performance and accuracy and identifying new mechanisms governing charge transport.
Kinetic Monte Carlo charge transport simulations are a powerful tool for understanding the electrical properties of disordered organic semiconductors. However, the simulations are computationally intensive, particularly when sites of low energy are strongly coupled. A hybrid algorithm that combines Monte Carlo method with the Chemical Master equation is proposed. By dynamically applying the Chemical Master equation, the state space of problematic regions can be coarsened leading to performant algorithms. Testing of the hybrid method shows that it is able to accurately reproduce the dynamics with less than 5 % error while achieving large performance gains. Speedup, particularly in disordered systems, has been shown to increase by several orders of magnitude.
Application of kinetic Monte Carlo charge transport simulations to organic semiconductors has helped clarify how energetic correlations effect the charge carrier mobility. A seeded nucleation mechanism was proposed to help explain charge transport in non-polar organic semiconductors exhibiting an exponential density of states (DOS). A heuristic implementation of the mechanism is able to both account for Poole-Frenkel behavior at low fields and the exponential tails observed in the DOS.
Finally, a multi-scale approach has been leveraged to correlate the molecular structure of PTB7 and PCE10 with their electronic DOS. Improvements in the methodology are proposed through a fragment basis method and tested on PTB7 and PCE10. Performance improvements are achieved by reducing the self consistent calculations to the linear scaling regime. Comparison with full ab initio calculations show the fragment basis approach is able to accurately reproduce the molecular orbital energies and wave functions. The DOS of PTB7 show excellent qualitative agreement with experimental results found in the literature.
|Commitee:||McLeod, Robert, Park, Wounjhang, Larsen, Ross, Glaser, Matthew, Baumeier, Björn|
|School:||University of Colorado at Boulder|
|School Location:||United States -- Colorado|
|Source:||DAI-B 81/7(E), Dissertation Abstracts International|
|Subjects:||Computational physics, Computational chemistry, Electrical engineering|
|Keywords:||Charge transport, Correlations, Master equation, Monte Carlo, Tight binding|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be