The spectral line-shape of the mid-IR absorption spectrum provides valuable information about the "hole" polaron coherence length in doped and undoped conjugated polymer films. In poly(3-hexylthiophene) (P3HT) films the spectrum generally consists of a narrow, low-energy peak A (700-1000 $cm^{-1}$) followed by a much broader, higher-energy peak B (2500-5000 $cm^{-1}$). Using a theory based on the Holstein Hamiltonian for mobile holes in P3HT, the IR line-shape is successfully reproduced for several recently measured spectra recorded in doped and undoped films, confirming the association of an enhanced peak ratio (A/B) with extended polaron coherence. Emphasis is placed on the origin of components polarized along the intra- and inter-chain directions and their dependence on the spatial distribution of disorder as well as the position of the dopant relative to the $\pi$-stack. The model is further adapted to treat donor-acceptor copolymers where the local HOMO energy varies periodically from donor unit to acceptor unit. The calculated line shape for a diketopyrrolopyrrole-based copolymer agrees well with the recently measured spectrum. / Chemistry
| Identifer | oai:union.ndltd.org:TEMPLE/oai:scholarshare.temple.edu:20.500.12613/1294 |
| Date | January 2019 |
| Creators | Ghosh, Raja |
| Contributors | Spano, Francis C., Matsika, Spiridoula, Carnevale, Vincenzo, Voelz, Vincent |
| Publisher | Temple University. Libraries |
| Source Sets | Temple University |
| Language | English |
| Detected Language | English |
| Type | Thesis/Dissertation, Text |
| Format | 191 pages |
| Rights | IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available., http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | http://dx.doi.org/10.34944/dspace/1276, Theses and Dissertations |
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