Tunable Dopants with Intrinsic Counterion Separation Reveal the Effects of Electron Affinity on Dopant Intercalation and Free Carrier Production in Sequentially Doped Conjugated Polymer Films
| Autor: | Taylor J. Aubry, Victoria M. Basile, Charlene Z. Salamat, Sarah H. Tolbert, Benjamin J. Schwartz, Alexander M. Spokoyny, Matthew J. Bird, Minh Dinh Phan, K. J. Winchell, Julia M. Stauber, Rebecca M. Kubena, Jonathan C. Axtell, Jeffrey Lindemuth |
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| Rok vydání: | 2020 |
| Předmět: |
inorganic chemicals
Electron mobility Materials science 02 engineering and technology 010402 general chemistry Polaron 01 natural sciences counterion distance Biomaterials Engineering redox‐driven infiltration Electron affinity molecular dopants Electrochemistry Materials tunable electron affinity redox-driven infiltration chemistry.chemical_classification Dopant doping efficiency electronic offset semiconducting polymers Doping Polymer Full Papers 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences Electronic Optical and Magnetic Materials chemistry Chemical physics Physical Sciences Chemical Sciences Neutron reflectometry Counterion 0210 nano-technology |
| Zdroj: | Advanced functional materials, vol 30, iss 28 Adv Funct Mater |
| Popis: | Carrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)‐based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox‐potential‐driven. Remarkably, X‐ray scattering shows that despite their large 2‐nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film. |
| Databáze: | OpenAIRE |
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