Tunneling and hopping conduction in Langmuir-Blodgett thin films of poly(3-hexylthiophene)

Eero Punkka, Michael Rubner, Jeff Hettinger, James Brooks, Scott Hannahs

Research output: Contribution to journalArticleScientificpeer-review

40 Citations (Scopus)

Abstract

The electrical conductivity and field-effect mobility of undoped and NOPF6-doped Langmuir-Blodgett thin films of poly(3-hexylthiophene) have been measured as a function of temperature, electric field, and film thickness. These properties are compared with those of free-standing films. In undoped samples the conductivity is best described by variable-range hopping, whereas in the doped and dedoped states the model of charging-energy-limited tunneling between conducting islands is applicable. The data indicate metallic charge carrier densities within the conducting islands in the highly doped state. At electric fields close to the dielectric breakdown, a possible onset to Fowler-Nordheim tunneling is observed. As the samples become dedoped, the electrical properties indicate an increase in the average size of conducting islands, which are suggested to consist of polymer backbones separated by the alkyl side chains of neighboring molecules.
Original languageEnglish
Pages (from-to)9076 - 9086
Number of pages11
JournalPhysical Review B: Condensed Matter
Volume43
Issue number11
DOIs
Publication statusPublished - 1991
MoE publication typeA1 Journal article-refereed

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