Elsner, Jan;
(2024)
Simulation of Charge Transport and Thermoelectricity in High Mobility Organic Semiconductors.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Organic semiconductors (OS) offer multiple advantages over conventional inorganic semiconductors, including cost-effective processing and flexibility. However, current state-of-the-art charge carrier mobilities are considerably lower than for in- organics, limiting widespread adoption of these materials. A detailed theoretical understanding of charge transport in OS is important for advancing materials design, yet challenging due to the complex interplay of electronic and electron-nuclear interactions. It has been shown that transport in these materials takes place in a unique regime featuring transient delocalization (TD) of the charge carriers, bridging the traditional perturbative limits of band and hopping theories. The aim of this thesis is to understand how transport in the TD regime plays out when (i) mechanical strain is applied (ii) temperature is changed (iii) a thermal gradient is applied. An important theme throughout is the effect of dynamic electronic disorder due to thermal nuclear motion. In crystalline rubrene – a benchmark OS with record carrier mobility – this is found to be critical in determining its mechanoelectric response, temperature dependence of mobility and, strikingly, efficacy of thermoelectric transport i.e. transport in the presence of a temperature gradient. The latter finding constitutes a novel picture of thermoelectric transport in the regime pertaining to high mobility OS. Finally, theoretical investigation of a far less-explored pyrene-based covalent organic framework, pyr-COF, reveals significantly larger electronic coupling and smaller electronic disorder than in rubrene, illustrating the possibility for very large charge carrier mobility in this class of OS.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Simulation of Charge Transport and Thermoelectricity in High Mobility Organic Semiconductors |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10187258 |
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