Charge-Transfer Intermediates in the Electrochemical Doping Mechanism of Conjugated Polymers
| Autor: | Lisa R. Savagian, John R. Reynolds, Carlos Silva, Ilaria Bargigia, Anna M. Österholm |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Quenching (fluorescence) Chemistry Exciton General Chemistry Conjugated system 010402 general chemistry Polaron 01 natural sciences Biochemistry Catalysis Molecular electronic transition 0104 chemical sciences Electrochemical cell symbols.namesake Colloid and Surface Chemistry Chemical physics Ultrafast laser spectroscopy symbols Physics::Chemical Physics Raman spectroscopy Electrochemical potential |
| Popis: | In this work, we address the nature of electrochemically induced charged states in conjugated polymers, their evolution as a function of electrochemical potential, and their coupling to their local environment by means of transient absorption and Raman spectroscopies synergistically performed in situ throughout the electrochemical doping process. In particular, we investigate the fundamental mechanism of electrochemical doping in an oligoether-functionalized 3,4-propylenedioxythiophene (ProDOT) copolymer. The changes embedded in both linear and transient absorption features allow us to identify a precursor electronic state with charge-transfer (CT) character that precedes polaron formation and bulk electronic conductivity. This state is shown to contribute to the ultrafast quenching of both neutral molecular excitations and polarons. Raman spectra relate the electronic transition of this precursor state predominantly to the Cβ -Cβ stretching mode of the thiophene heterocycle. We characterize the coupling of the CT-like state with primary excitons and electrochemically induced charge separated states, providing insight into the energetic landscape of a heterogeneous polymer-electrolyte system and demonstrate how such coupling depends on environmental parameters, such as polymer structure, electrolyte composition, and environmental polarity. |
| Databáze: | OpenAIRE |
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