Unified Understanding of Molecular Weight Dependence of Electron Transport in Naphthalene Diimide-Based n‑Type Semiconducting Polymers
Electron transport is critical to the use of n-type semiconducting polymers in diverse electronic and optoelectronic devices. Herein, we combine measurements of field-effect electron mobility and bulk electron mobility with thin-film microstructure characterization to elucidate the polymer chain len...
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Veröffentlicht in: | Chemistry of materials 2022-11, Vol.34 (21), p.9644-9655 |
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Hauptverfasser: | , , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Electron transport is critical to the use of n-type semiconducting polymers in diverse electronic and optoelectronic devices. Herein, we combine measurements of field-effect electron mobility and bulk electron mobility with thin-film microstructure characterization to elucidate the polymer chain length dependence of electron transport in n-type semiconducting polymers, exemplified by a naphthalene diimide-biselenophene copolymer, PNDIBS. Both bulk electron mobility measured by the space–charge limited current method and field-effect electron mobility of PNDIBS and other n-type semiconducting copolymers exhibit a peak at a critical degree of polymerization (DPc) of 45–60 repeat units. The decreased electron mobility below DPc is shown to originate from reduced intercrystallite connectivity while above DPc, intrachain twisting/folding, interchain entanglements, and intracrystallite limitations dominate electron transport. These findings provide a unified picture of the effects of polymer molecular weight on electron transport in naphthalene diimide-based polymers and offer a more quantitative design rule for high-mobility n-type polymers with donor–acceptor architecture. |
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ISSN: | 0897-4756 1520-5002 |
DOI: | 10.1021/acs.chemmater.2c02357 |