Charge-Transfer Intermediates in the Electrochemical Doping Mechanism of Conjugated Polymers

08 October 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


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.


ultrafast spectroscopy
conjugated polymers
electrochemical doping
electrochemical cells

Supplementary materials

SI ProDOT spectroscopy Paper 10-05


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.