Dodecaborane‐Based Dopants Designed to Shield Anion Electrostatics Lead to Increased Carrier Mobility in a Doped Conjugated Polymer

Journal Article · Tue Jan 22 23:00:00 EST 2019 · Advanced Materials

DOI:https://doi.org/10.1002/adma.201805647· OSTI ID:1491925

Aubry, Taylor J. ^[1]; Axtell, Jonathan C. ^[1]; Basile, Victoria M. ^[1]; Winchell, K. J. ^[1]; Lindemuth, Jeffrey R. ^[2]; Porter, Tyler M. ^[3]; Liu, Ji‐Yuan ^[4]; Alexandrova, Anastassia N. ^[5]; Kubiak, Clifford P. ^[3]; Tolbert, Sarah H. ^[6]; Spokoyny, Alexander M. ^[5]; Schwartz, Benjamin J. ^[5]

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1. Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095‐1569 USA
2. Lake Shore Cryotronics Westerville OH 43082 USA
3. Department of Chemistry and Biochemistry University of California, San Diego La Jolla CA 92093 USA
4. Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095‐1569 USA, Key Laboratory for Advanced Materials Center for Computational Chemistry and Research Institute of Industrial Catalysis School of Chemistry and Molecular Engineering East China University of Science and Technology Shanghai 200237 P. R. China
5. Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095‐1569 USA, California NanoSystems Institute University of California, Los Angeles Los Angeles CA 90095‐1569 USA
6. Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095‐1569 USA, California NanoSystems Institute University of California, Los Angeles Los Angeles CA 90095‐1569 USA, Department of Materials Science and Engineering University of California, Los Angeles Los Angeles CA 90095‐1569 USA

Abstract

One of the most effective ways to tune the electronic properties of conjugated polymers is to dope them with small‐molecule oxidizing agents, creating holes on the polymer and molecular anions. Undesirably, strong electrostatic attraction from the anions of most dopants localizes the holes created on the polymer, reducing their mobility. Here, a new strategy utilizing a substituted boron cluster as a molecular dopant for conjugated polymers is employed. By designing the cluster to have a high redox potential and steric protection of the core‐localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained. AC Hall effect measurements show that P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with F ₄ TCNQ, even though the boron‐cluster‐doped films have poor crystallinity. Moreover, the number of free carriers approximately matches the number of boron clusters, yielding a doping efficiency of ≈100%. These results suggest that shielding the polaron from the anion is a critically important aspect for producing high carrier mobility, and that the high polymer crystallinity required with dopants such as F ₄ TCNQ is primarily to keep the counterions far from the polymer backbone.

• Sponsoring Organization: USDOE
• Grant/Contract Number: NONE; AC02-76SF00515
• OSTI ID: 1491925
• Journal Information: Advanced Materials, Journal Name: Advanced Materials Journal Issue: 11 Vol. 31; ISSN 0935-9648
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English