Chain Dynamics, Relaxation Times, and Conductivities of Bithiophene–Acene Copolymers Measured Using High Frequency Saturation Transfer EPR
| Autor: | Alicia M. Fraind, John D. Tovar, Lev R. Ryzhkov |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Conductive polymer
Anthracene Diffusion Relaxation (NMR) 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films law.invention chemistry.chemical_compound chemistry Polymerization law Polymer chemistry Materials Chemistry Spin diffusion Physical chemistry Condensed Matter::Strongly Correlated Electrons Physical and Theoretical Chemistry 0210 nano-technology Electron paramagnetic resonance Acene |
| Zdroj: | The Journal of Physical Chemistry B. 120:1033-1039 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/acs.jpcb.5b11212 |
| Popis: | We present a study to probe the formation of localized aromatic sextets and their effects on the charge transport properties in polymers with acene cores. Bithiophene-acene copolymers containing benzene, naphthalene, or anthracene as acene cores were synthesized using Yamamoto polymerization. Drop-casted polymer films were chemically doped and analyzed using high frequency saturation transfer EPR (HF ST-EPR), a method which has proven useful in the study of conducting polymers. The spin-spin and spin-lattice relaxation times were determined for these polymers at low temperatures (4 to 20 K) and used to obtain inter- and intrachain spin diffusion rates and conductivities. Similar interchain spin diffusion rates were seen across all polymer systems; however, anthracene containing polymer poly(hexylTTATT) was found to have the largest intrachain spin diffusion rate. The poly(hexylTTATT) intrachain spin diffusion rate may be artificially high if the anthracene ring restricts the diffusion of spin to the hexylated quaterthiophene segment in poly(hexylTTATT) whereas the spins diffuse through the acene cores in the benzene and naphthalene derivatives. Alternatively, as both the spin diffusion rates and conductivities vary unpredictably with temperature, it is possible that the π-electron localization previously seen in the anthracene core could be relieved at lower temperatures. |
| Databáze: | OpenAIRE |
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